Sedentary Research Database

There are 179 articles in the Sedentary Research Database. If you would like to add an article to the database, please submit the PubMed ID.


Arciero PJ, Smith DL, Calles-Escandon J. Effects of short-term inactivity on glucose tolerance, energy expenditure, and blood flow in trained subjects. J Appl Physiol. 1998 Apr;84(4):1365-73.

The purpose of this investigation was to examine the effects of 7-10 days of inactivity (IA) on glucose tolerance (GT), resting metabolic rate (RMR), thermic effect of a meal (TEM), and limb blood flow in endurance-trained men. Eight highly trained (peak O2 consumption 64 +/- 2 ml . kg-1 . min-1) endurance athletes participated in this study involving two identical test days, one approximately 24 h after a normal training bout (Tr) and the second after 7-10 days of IA. The following tests were conducted at each visit: 75-g oral glucose tolerance test (OGTT), RMR, and TEM and measurements of calf and forearm blood flow (BF) by using venous occlusive plethysmography. Body weight remained unchanged during this short period of IA (Tr, 78.5 +/- 1 kg; IA, 78.7 +/- 1 kg). The area under the glucose and insulin curves increased 65% (Tr, 3,375 +/- 877 vs. IA, 5,559.4 +/- 621 mg . dl-1 . 180 min-1) and 73% (Tr, 2,182.5 +/- 270 vs. IA, 3,793.1 +/- 739 microU . ml-1 . 180 min-1) after IA, respectively (P < 0.01). RMR decreased significantly (4%; 1.5 +/- 0. 02 vs. 1.44 +/- 0.02 kcal/min; P < 0.05) and respiratory exchange ratio during the OGTT increased (4%, 0.812 +/- 0.011 vs. 0.842 +/- 0. 009; P < 0.05) after IA, whereas TEM increased similarly in the Tr and IA states. In the Tr state, mean calf BF increased by 22% (3.17 +/- 0.22 vs. 3.87 +/- 0.38 ml . 100 ml-1 . min-1; P < 0.05) during the OGTT but remained unchanged after IA, whereas no differences at rest or during OGTTs existed between the two conditions for forearm BF. Incremental insulin area above fasting during the OGTT was correlated with mean calf BF in the Tr (r = 0.76, P < 0.05) and IA (r = 0.72, P < 0.05) states. In conclusion, 7-10 days of IA results in a deterioration in GT and a reduction in RMR. After glucose ingestion, calf BF was elevated compared with resting levels in the Tr state but was unchanged in the IA state; however, limb BF was not related to GT or RMR. Thus our findings raise questions regarding the relative contribution of BF in modulating glucose tolerance and energy expenditure in endurance athletes in their habitual Tr or IA state.
Atkin AJ, Gorely T, Biddle SJ, Marshall SJ, Cameron N. Critical hours: physical activity and sedentary behavior of adolescents after school. Pediatr Exerc Sci. 2008 Nov;20(4):446-56.

The present study examined physical activity and sedentary behavior patterns of adolescents between 15.30h and 18.30h. The sample for this study is 1,484 (boys: n = 561; girls: n = 923). Boys and girls reported 21 and 19 min of physical activity and 24 and 26 min of homework respectively during this period. Technology-based sedentary behavior (TV viewing, computer and video game use) was significantly higher in boys than girls (boys = 50 mins; girls = 35 mins; p < .05). The most prevalent behaviors after school are technology-based sedentary behavior, homework and physical activity. During these hours, engagement in physical activity does not appear to displace time spent doing homework.
Bassett DR Jr, Freedson P, Kozey S. Medical hazards of prolonged sitting. Exerc Sport Sci Rev. 2010 Jul;38(3):101-2.

[No abstract available.]
Bellettiere J1, Carlson JA2, Rosenberg D3, Singhania A4, Natarajan L4, Berardi V5, LaCroix AZ4, Sears DD4, Moran K4, Crist K4, Kerr J4. Gender and Age Differences in Hourly and Daily Patterns of Sedentary Time in Older Adults Living in Retirement Communities. PLoS One. 2015 Aug 21;10(8):e0136161. doi: 10.1371/journal.pone.0136161. eCollection 2015.

BACKGROUND: Total sedentary time varies across population groups with important health consequences. Patterns of sedentary time accumulation may vary and have differential health risks. The purpose of this study is to describe sedentary patterns of older adults living in retirement communities and illustrate gender and age differences in those patterns.METHODS: Baseline accelerometer data from 307 men and women (mean age = 84±6 years) who wore ActiGraph GT3X+ accelerometers for ? 4 days as part of a physical activity intervention were classified into bouts of sedentary time (<100 counts per minute). Linear mixed models were used to account for intra-person and site-level clustering. Daily and hourly summaries were examined in mutually non-exclusive bouts of sedentary time that were 1+, 5+, 10+, 20+, 30+, 40+, 50+, 60+, 90+ and 120+ minutes in duration. Variations by time of day, age and gender were explored.RESULTS: Men accumulated more sedentary time than women in 1+, 5+, 10+, 20+, 30+, 40+, 50+ and 60+ minute bouts; the largest gender-differences were observed in 10+ and 20+ minute bouts. Age was positively associated with sedentary time, but only in bouts of 10+, 20+, 30+, and 40+ minutes. Women had more daily 1+ minute sedentary bouts than men (71.8 vs. 65.2), indicating they break up sedentary time more often. For men and women, a greater proportion of time was spent being sedentary during later hours of the day than earlier. Gender differences in intra-day sedentary time were observed during morning hours with women accumulating less sedentary time overall and having more 1+ minute bouts.CONCLUSIONS: Patterns identified using bouts of sedentary time revealed gender and age differences in the way in which sedentary time was accumulated by older adults in retirement communities. Awareness of these patterns can help interventionists better target sedentary time and may aid in the identification of health risks associated with sedentary behavior. Future studies should investigate the impact of patterns of sedentary time on healthy aging, disease, and mortality.
Bennett JA, Winters-Stone K, Nail LM, Scherer J. Definitions of sedentary in physical-activity-intervention trials: a summary of the literature. J Aging Phys Act. 2006 Oct;14(4):456-77.

This review describes the definitions of sedentary used to screen community-dwelling adults in physical-activity-intervention trials published from 2000 to 2005. Results of 42 trials showed that definitions of sedentary varied from <20 to <150 min/week of physical activity, and few reported the type (work, household, or leisure) or intensity of activity that was used to screen participants. The range of “sedentary” samples makes it difficult to compare trial results or generalize findings. Published reports of exercise trials would be more useful to practitioners and researchers if they included an explicit description of the cut point used to define sedentary adults in the sample, in terms of maximum minutes or days per week of activity and the wording of the screening measure in terms of type and intensity of activity.
Bergouignan A, Rudwill F, Simon C, Blanc S. Physical inactivity as the culprit of metabolic inflexibility: Evidences from bed-rest studies. J Appl Physiol. 2011 Aug 11. [Epub ahead of print]

Although it is no longer debatable that sedentary behaviors are an actual cause of many metabolic diseases, the physiology of physical inactivity has been poorly investigated for this purpose. Along with microgravity, the physiological adaptations to space flights require metabolic adaptations to physical inactivity and that is exceedingly well simulated during the ground-based microgravity bed-rest analogs. Bed-rest thus represents a unique model to investigate the mechanisms by which physical inactivity leads to the development of current societal chronic diseases. For decades, however, clinicians and physiologists working in space research have worked separately without taking full awareness of potential strong mutual questioning. This review summarizes the data collected over the last 60 years on metabolic adaptations to bed-rest in healthy subjects. Our aim is to provide evidence which support the hypothesis that physical inactivity per se is one of the primary causes in the development of metabolic inflexibility. This evidence will focus on four main tenants of metabolic inflexiblity: 1) insulin resistance, 2) impaired lipid trafficking and hyperlipidemia, 3) a shift in substrate use towards glucose, 4) a shift in muscle fiber type and ectopic fat storage. Altogether, this hypothesis places sedentary behaviors upstream on the list of factors involved in metabolic inflexibility which is considered to be a primary impairment in several metabolic disorders such as obesity, insulin-resistance and type 2 diabetes mellitus.
Bernstein MS, Morabia A, Sloutskis D. Definition and prevalence of sedentarism in an urban population. Am J Public Health. 1999 Jun;89(6):862-7.

OBJECTIVES: The present study sought to formulate a precise definition of sedentarism and to identify activities performed by active people that could serve as effective preventive goals.METHODS: A population-based sample of 919 residents of Geneva, Switzerland, aged 35 to 74 years, completed a 24-hour recall. Sedentary people were defined as those expending less than 10% of their daily energy in the performance of moderate- and high-intensity activities (at least 4 times the basal metabolism rate).RESULTS: The rates of sedentarism were 79.5% in men and 87.2% in women. Among sedentary and active men, average daily energy expenditures were 2600 kcal (95% confidence interval [CI] = 2552, 2648) and 3226 kcal (95% CI = 3110, 3346), respectively; the corresponding averages for women were 2092 kcal (95% CI = 2064, 2120) and 2356 kcal (95% CI = 2274, 2440). The main moderate- and high-intensity activities among active people were sports (tennis, gymnastics, skiing), walking, climbing stairs, gardening, and (for men only) occupational activities.CONCLUSIONS: The definition of sedentarism outlined in this article can be reproduced in other populations, allows comparisons across studies, and provides preventive guidelines in that the activities most frequently performed by active people are the ones most likely to be adopted by their sedentary peers.
Bey L, Akunuri N, Zhao P, Hoffman EP, Hamilton DG, Hamilton MT. Patterns of global gene expression in rat skeletal muscle during unloading and low-intensity ambulatory activity. Physiol Genomics. 2003 Apr 16;13(2):157-67.

Physical inactivity and unloading lead to diverse skeletal muscle alterations. Our goal was to identify the genes in skeletal muscle whose expression is most sensitive to periods of unloading/reduced physical activity and that may be involved in triggering initial responses before phenotypic changes are evident. The ability of short periods of physical activity/loading as an effective countermeasure against changes in gene expression mediated by inactivity was also tested. Affymetrix microarrays were used to compare mRNA levels in the soleus muscle under three experimental treatments (n = 20-29 rats each): 12-h hindlimb unloading (HU), 12-h HU followed by 4 h of intermittent low-intensity ambulatory and postural activity (4-h reloading), and control (with ambulatory and postural activity). Using a combination of criteria, we identified a small set of genes (approximately 1% of 8,738 genes on the array or 4% of significant expressed genes) with the most reproducible and largest responses to altered activity. Analysis revealed a coordinated regulation of transcription for a large number of key signaling proteins and transcription factors involved in protein synthesis/degradation and energy metabolism. Most (21 of 25) of the gene expression changes that were downregulated during HU returned at least to control levels during the reloading. In surprising contrast, 27 of 38 of the genes upregulated during HU remained significantly above control, but most showed trends toward reversal. This introduces a new concept that, in general, genes that are upregulated during unloading/inactivity will be more resistant to periodic reloading than those genes that are downregulated. This study reveals genes that are the most sensitive to loading/activity in rat skeletal muscle and indicates new targets that may initiate muscle alterations during inactivity.
Bey L, Hamilton MT. Suppression of skeletal muscle lipoprotein lipase activity during physical inactivity: a molecular reason to maintain daily low-intensity activity. J Physiol. 2003 Sep 1;551(Pt 2):673-82. Epub 2003 Jun 18.

We have examined the regulation of lipoprotein lipase (LPL) activity in skeletal muscle during physical inactivity in comparison to low-intensity contractile activity of ambulatory controls. From studies acutely preventing ambulatory activity of one or both the hindlimbs in rats, it was shown that approximately 90-95 % of the heparin-releasable (HR) LPL activity normally present in rat muscle with ambulatory activity is lost, and thus dependent on local contractile activity. Similarly, approximately 95 % of the differences in LPL activity between muscles of different fibre types was dependent on ambulatory activity. The robustness of the finding that physical inactivity significantly decreases muscle LPL activity was evident from confirmatory studies with different models of inactivity, in many rats and mice, both sexes, three muscle types and during both acute and chronic (11 days) treatment. Inactivity caused a local reduction of plasma [3H]triglyceride uptake into muscle and a decrease in high density lipoprotein cholesterol concentration. LPL mRNA was not differentially expressed between ambulatory controls and either the acutely or chronically inactive groups. Instead, the process involved a rapid loss of the HR-LPL protein mass (the portion of LPL largely associated with the vascular endothelium) by an actinomycin D-sensitive signalling mechanism (i.e. transcriptionally dependent process). Significant decreases of intracellular LPL protein content lagged behind the loss of HR-LPL protein. Treadmill walking raised LPL activity approximately 8-fold (P < 0.01) within 4 h after inactivity. The striking sensitivity of muscle LPL to inactivity and low-intensity contractile activity may provide one piece of the puzzle for why inactivity is a risk factor for metabolic diseases and why even non-vigorous activity provides marked protection against disorders involving poor lipid metabolism.
Biddle SJ, Gorely T, Marshall SJ, Cameron N. The prevalence of sedentary behavior and physical activity in leisure time: A study of Scottish adolescents using ecological momentary assessment. Prev Med. 2009 Feb;48(2):151-5. Epub 2008 Nov 11.

OBJECTIVE: To report time and prevalence of leisure time sedentary and active behaviors in adolescents.METHOD: Cross-sectional, stratified, random sample from schools in 14 districts in Scotland, 2002-03, using ecological momentary assessment (n=385 boys, 606 girls; mean age 14.1 years; range 12.6-16.7 years). This is a method of capturing current behavioral episodes. We used 15 min time intervals.RESULTS: Television viewing occupied the most leisure time. The five most time consuming sedentary activities occupied 228 min per weekday and 396 min per weekend day for boys, and 244 min per weekday and 400 min per weekend day for girls, with TV occupying one-third to one-half of this time. In contrast, 62 min was occupied by active transport and sports/exercise per weekday and 91 min per weekend day for boys, with 55 min per weekday and 47 min per weekend day for girls. A minority watched more than 4 h of TV per day, with more at weekends. Other main sedentary behaviors for boys were homework, playing computer/video games, and motorised transport and, for girls, homework, motorised transport, and sitting and talking.CONCLUSION: Scottish adolescents engage in a variety of sedentary and active behaviors. Research into sedentary behavior must assess multiple behaviors and not rely solely on TV viewing.
Biddle SJ, Gorely T, Stensel DJ. Health-enhancing physical activity and sedentary behaviour in children and adolescents. J Sports Sci. 2004 Aug;22(8):679-701.

We provide a wide-ranging review of health-related physical activity in children and adolescents using a behavioural epidemiology framework. In contrast to many other reviews, we highlight issues associated with true sedentary behaviours alongside physically active behaviours. Specifically, we review the evidence concerning the links between physical activity and cardiovascular disease, overweight and obesity, psychosocial measures, type II diabetes, and skeletal health. Although the evidence is unconvincing at times, several factors lead to the conclusion that promoting physical activity in youth is desirable. A review of the prevalence of physical activity and sedentary behaviours shows that many young people are active, but this declines with age. A substantial number are not adequately active for health benefits and current trends in juvenile obesity are a cause for concern. Prevalence data on sedentary behaviours are less extensive but suggest that total media use by young people has not changed greatly in recent years. Most children and adolescents do not exceed recommended daily hours of TV viewing. Physical activity is unrelated to TV viewing. We also identified the key determinants of physical activity in this age group, highlighting demographic, biological, psychological, behavioural, social and environmental determinants. Interventions were considered for school, family and community environments. Finally, policy recommendations are offered for the education, governmental, sport and recreation, health, and mass media sectors.
Black AE, Coward WA, Cole TJ, Prentice AM. Human energy expenditure in affluent societies: an analysis of 574 doubly-labelled water measurements. Eur J Clin Nutr. 1996 Feb;50(2):72-92.

OBJECTIVES: To describe average levels of free-living energy expenditure in people from affluent societies and to determine the influence of body weight, height, age and sex.DESIGN: Analysis of 574 measurements of total energy expenditure (TEE, assessed by the doubly-labelled water method); basal metabolic rate (BMR, directly measured or derived from similar directly measured proxy measures such as during sleep); activity energy expenditure (AEE, derived as TEE-BMR); and physical activity level (PAL, derived as TEE/BMR) from people aged 2-95 years. The dataset was extracted from 1614 published and unpublished measurements in 1156 subjects after exclusion of repeat estimates and subjects in special physiological or behavioural states (eg pregnancy, athletic or military training etc).RESULTS: A separate analysis of data from non-ambulant subjects, and from elite endurance athletes (all excluded from the main dataset) established the limits of human daily energy expenditure at around 1.2 x BMR and 4.5 x BMR. In the main analysis, the validity of PAL as an index of TEE adjusted for BMR was tested and confirmed. Regression equations were then derived to describe TEE, BMR, AEE and PAL in terms of body weight, height, age and sex. As anticipated, TEE, BMR and AEE were all positively related to weight and height, while age was a negative predictor, especially of activity. The influence of weight disappeared when TEE was expressed as PAL, but height and age remained as highly significant predictors. For all three components, females expended 11% less energy on average than males after adjustment for weight, height and age. Average levels of energy expenditure in different age and sex groups are tabulated.CONCLUSIONS: There now exists a large and robust database of energy expenditure measurements obtained by the doubly-labelled water method. Analysis of the data from affluent societies shows that, in general, levels of energy expenditure are similar to the recommendations for energy requirements adopted by FAO/WHO/UNU (1985) and UK Department of Health (1991). PAL values for active subjects tend to be higher than is currently assumed. The current analysis provides a substantial body of normal data against which other estimates can be compared.
Booth FW, Hargreaves M. Understanding multi-organ pathology from insufficient exercise. J Appl Physiol. 2011 Aug 18. [Epub ahead of print]

Bouchard DR1, Strachan S, Johnson L, Moola F, Chitkara R, McMillan D, Myrie S, Giesbrecht G. Using Shared Treadmill Workstations to Promote Less Time Spent in Daily Low Intensity Physical Activities: A Pilot Study. J Phys Act Health. 2015 Mar 31. [Epub ahead of print]

OBJECTIVE: To test the feasibility of sharing treadmill workstations among office workers to reduce time spent at low intensity, and explore changes in health outcomes after a three-month intervention.METHODS: Twenty-two office workers were asked to walk two hours per shift on a shared treadmill workstation for three months. Physical activity levels (i.e., low, light, moderate, and vigorous), health related measures (e.g., sleep, blood pressure), treadmill usage information, and questions regarding participants’ expectation and experiences were collected.RESULTS: Physical activity time at low intensity during work days was reduced by 20.1% (p=.007) in the 71% of participants completing the study. Participants were 70% confident that they would keep using the treadmill workstations. Interestingly, systolic blood pressure, diastolic blood pressure, and sleep quality scores were significantly improved (p<.05).DISCUSSION: The use of such equipment to replace a few hours of sitting is feasible and might offer important health benefits.
Brown CJ, Redden DT, Flood KL, Allman RM. The underrecognized epidemic of low mobility during hospitalization of older adults. J Am Geriatr Soc. 2009 Sep;57(9):1660-5. Epub 2009 Aug 4.

OBJECTIVES: To examine the proportion of time spent in three levels of mobility (lying, sitting, and standing or walking) by a cohort of hospitalized older veterans as measured by validated wireless accelerometers.DESIGN: A prospective, observational cohort study.SETTING: One hundred fifty-bed Department of Veterans Affairs hospital.PARTICIPANTS: Forty-five hospitalized medical patients, aged 65 and older who were not delirious, did not have dementia, and were able to walk in the 2 weeks before admission were eligible.MEASUREMENTS: Wireless accelerometers were attached to the thigh and ankle of patients for the first 7 days after admission or until hospital discharge, whichever came first. The mean proportion of time spent lying, sitting, and standing or walking was determined for each hour after hospital admission using a previously validated algorithm.RESULTS: Forty-five male patients (mean age 74.2) with a mean length of stay of 5.1 days generated 2,592 one-hour periods of data. A baseline functional assessment indicated that 35 (77.8%) study patients were willing and able to walk a short distance independently. No patient remained in bed the entire measured hospital stay, but on average, 83% of the measured hospital stay was spent lying in bed. The average amount of time that any one individual spent standing or walking ranged from a low of 0.2% to a high of 21%, with a median of 3%, or 43 minutes per day.CONCLUSION: This is the first study to continuously monitor mobility levels early during a hospital stay. On average, older hospitalized patients spent most of their time lying in bed, despite an ability to walk independently.
Carr, LJ and Mahar, MT Accuracy of Intensity and Inclinometer Output of Three ActivityMonitors for Identification of Sedentary Behavior and Light-Intensity Activity Carr, LJ, & Mahar, MT. Accuracy of Intensity and Inclinometer Output of Three Activity Monitors for Identification of Sedentary Behavior and Light Intensity Activity. Journal of Obesity, vol. 2012, Article ID 460271, 9 pages, 2012. doi:10.1155/2012/460271

Purpose. To examine the accuracy of intensity and inclinometer output of three physical activity monitors during various sedentary and light-intensity activities. Methods. Thirty-six participants wore three physical activity monitors (ActiGraph GT1M, ActiGraph GT3X+, and StepWatch) while completing sedentary (lying, sitting watching television, sitting using computer, and standing still) light (walking 1.0mph, pedaling 7.0mph, pedaling 15.0mph) intensity activities under controlled settings. Accuracy for correctly categorizing intensity was assessed for each monitor and threshold. Accuracy of the GT3X+ inclinometer function (GT3X+Incl) for correctly identifying anatomical position was also assessed. Percentage agreement between direct observation and the monitor recorded time spent in sedentary behavior and light intensity was examined. Results. All monitors using all thresholds accurately identified over 80% of sedentary behaviors and 60% of light-intensity walking time based on intensity output. The StepWatch was the most accurate in detecting pedaling time but unable to detect pedal workload. The GT3X+Incl accurately identified anatomical position during 70% of all activities but demonstrated limitations in discriminating between activities of differing intensity. Conclusions. Our findings suggest that all three monitors accurately measure most sedentary and light-intensity activities although choice of monitors should be based on study-specific needs.
Carson V, Iannotti RJ, Pickett W, Janssen I. Urban and rural differences in sedentary behavior among American and Canadian youth. Health Place. 2011 Jul;17(4):920-8. Epub 2011 Apr 29.

We examined relationships between urban-rural status and three screen time behaviors (television, computer, video games), and the potential mediating effect of parent and peer support on these relationships. Findings are based on American (n=8563) and Canadian (n=8990) youth in grades 6-10 from the 2005/06 Health Behavior in School-Aged Children Survey. Weekly hours of individual screen time behaviors were calculated. Urban-rural status was defined using the Beale coding system. Parent and peer support variables were derived from principal component analysis. In comparison to the referent group (non-metro adjacent), American youth in the most rural areas were more likely to be high television users and less likely to be high computer users. Conversely, Canadian youth in medium and large metropolitan areas were less likely to be high television users and more likely to be high computer users. Parent and peer support did not strongly mediate the relationships between urban-rural status and screen time. These findings suggest that interventions aiming to reduce screen time may be most effective if they consider residential location and the specific screen time behavior.Copyright © 2011 Elsevier Ltd. All rights reserved.
Castillo, M. Hinckson, E Measuring physical activity and sedentary behaviour at work: A review Castillo-Retamal, M., Hinckson, E.A. (2011). Measuring physical activity and sedentary behaviour at work: A review. WORK, 40, 345.357.

Abstract. Objective: To identify methods used to assess physical activity and sedentary behaviour at the workplace and review the validity and reliability of these measures. Methods: Databases were searched for relevant published articles including MEDLINE, SPORT Discus, ProQuest and Google Scholar. Keywords used were physical-activity, workplace, sedentary-behaviour, measurement and questionnaire. Studies included were original, written in English, published between 1990 and 2009, and focused on validated physical activity and sedentary behaviour measures at work. Eleven papers were identified in which three used criterion standards, three objective measures, and five subjective measures. Results: The most common method of data collection was through self-report, surveys or questionnaires. Physical activity measured with motion sensors, ranged from 4,422 to 10,334 steps/day (pedometers) and sedentary time ranged from 1.8 to 6 hours/day (h/d) (accelerometers). Self-report measures provided information relevant to the perception of physical activity at work (? 0.5 h/d), sitting time (> 3 h/d) and calculated energy expenditure (< 800 kcal/d). Conclusion: Physical activity levels at work were low while sedentary behaviour was high. This was largely a function of occupation (white-collar vs. blue-collar). None of the studies assessed validity or reliability of measures used however, instruments as assessed by others showed moderate to strong validity and reliability values. Keywords: Measurement, workplace, sitting time
Chaput JP, Klingenberg L, Astrup A, Sjödin AM. Modern sedentary activities promote overconsumption of food in our current obesogenic environment. Obes Rev. 2011 May;12(5):e12-20. doi: 10.1111/j.1467-789X.2010.00772.x.

Achieving body-weight stability is certainly challenging in today’s obesogenic environment. Every day we are surrounded and affected by stimuli that act on our behaviour. A common feature of these stimuli is that they increase our comfort and well-being, but unfortunately they promote a positive caloric balance. Intriguingly, the preponderance of sedentary lifestyles is not only a matter of the amount of calories expended. A careful examination of modern sedentary activities reveals that they also promote overconsumption of food. This is particularly the case with television viewing, video game playing, cognitive working, music listening and short sleeping. Moreover, the increased food intake in the absence of hunger observed with the practice of these modern-life activities emphasizes that the hedonic value of food intake plays an important role. These observations suggest that our quest for reward and pleasure is not fine tuned to our biology, and the development of coping strategies is needed.© 2010 The Authors. obesity reviews © 2010 International Association for the Study of Obesity.
Chaput JP, Visby T, Nyby S, Klingenberg L, Gregersen NT, Tremblay A, Astrup A, Sjödin A. Video game playing increases food intake in adolescents: a randomized crossover study. Am J Clin Nutr. 2011 Jun;93(6):1196-203. Epub 2011 Apr 13.

BACKGROUND: Video game playing has been linked to obesity in many observational studies. However, the influence of this sedentary activity on food intake is unknown.OBJECTIVE: The objective was to examine the acute effects of sedentary video game play on various components of energy balance.DESIGN: With the use of a randomized crossover design, 22 healthy, normal-weight, male adolescents (mean ± SD age: 16.7 ± 1.1 y) completed two 1-h experimental conditions, namely video game play and rest in a sitting position, followed by an ad libitum lunch. The endpoints were spontaneous food intake, energy expenditure, stress markers, appetite sensations, and profiles of appetite-related hormones.RESULTS: Heart rate, systolic and diastolic blood pressures, sympathetic tone, and mental workload were significantly higher during the video game play condition than during the resting condition (P < 0.05). Although energy expenditure was significantly higher during video game play than during rest (mean increase over resting: 89 kJ; P < 0.01), ad libitum energy intake after video game play exceeded that measured after rest by 335 kJ (P < 0.05). A daily energy surplus of 682 kJ (163 kcal) over resting (P < 0.01) was observed in the video game play condition. The increase in food intake associated with video game play was observed without increased sensations of hunger and was not compensated for during the rest of the day. Finally, the profiles of glucose, insulin, cortisol, and ghrelin did not suggest an up-regulation of appetite during the video game play condition.CONCLUSION: A single session of video game play in healthy male adolescents is associated with an increased food intake, regardless of appetite sensations. The trial was registered at as NCT01013246.Comment inAm J Clin Nutr. 2011 Oct;94(4):1150-1; author reply 1151-2.
Ching PL, Willett WC, Rimm EB, Colditz GA, Gortmaker SL, Stampfer MJ. Activity level and risk of overweight in male health professionals. Am J Public Health. 1996 Jan;86(1):25-30.

OBJECTIVES: This study undertook to examine relationships between nonsedentary activity level, time spent watching television (TV)/videocassette recorder (VCR), and risk of overweight among men.METHODS: Men participating in the Health Professionals Follow-Up Study were mailed surveys. Cross-sectional analyses examined the prevalence and odds of being overweight, prospective analyses determined cumulative incidence rates and relative risks of becoming overweight over 2 years of follow-up.RESULTS: Cross-sectionally, odds of being overweight were 50% (95% confidence interval [CI] = 45%; 55%) lower for men in the highest quintile of nonsedentary activity level when compared with men in the lowest quintile. Among men watching 41 or more hours of TV/VCR per week, the odds of being overweight were 406 (95% CI = 2.67, 6.17) times greater than those for men watching no more than 1 hour per week. Prospectively, higher levels is of nonsedentary activity and lower levels of TV/VCR viewing were independently associated with lower relative risks for becoming overweight between survey years.CONCLUSIONS: Both a lack of nonsedentary activity and time spent watching TV/VCR contribute to the development of overweight in men. Sedentary and nonsedentary activities represent separate domains, each with independent risks for overweight.
Clark BK, Healy GN, Winkler EA, Gardiner PA, Sugiyama T, Dunstan DW, Matthews CE, Owen N. Relationship of television time with accelerometer-derived sedentary time: NHANES. Med Sci Sports Exerc. 2011 May;43(5):822-8.

PURPOSE: To examine the relationship of self-reported television (TV) viewing time with accelerometer-derived total sedentary time and to determine whether it differs by subgroup.METHODS: Using data for adults (?20 yr) from the 2003-2004 and 2005-2006 nationally representative US National Health and Nutrition Examination Surveys (NHANES; n=5738), linear regression models examined the associations of categories of self-reported TV viewing time (<1, 1, 2, 3, 4, and >5 h·d) with accelerometer-derived sedentary time (<100 counts per minute; h·d). Spearman ? assessed the correlation between participants’ rankings on the two measures. Analyses were stratified by gender, age, race/ethnicity, and, in the 2003-2004 NHANES cycle, by work status among working-aged adults (20-65 yr, n=2069).RESULTS: TV viewing time was significantly associated with sedentary time, with positive associations for all gender, age, race/ethnicity groups, and for those not working or working part-time, but not for those in full-time work. However, correlations between rankings of the measures were only “fair” overall (?=0.22) and were similar for all gender and racial/ethnic groups and for those of mid- and older age but not for those of younger age (20-39 yr, ?=0.05). In the working-aged subgroup, there was also a fair correlation between the measures for those not working (?=0.22) but no significant correlation for those in part-time (?=0.14) or full-time work (?=0.03).CONCLUSIONS: Associations of TV viewing time with accelerometer-derived total sedentary time were statistically significant, but correlations were of only fair magnitude, and the strength of the relationship was not consistent across all population subgroups. These findings suggest that TV viewing time has an influence on overall sedentary time at a population level; however, measurement of sedentary time in other domains is also important.© 2011 by the American College of Sports Medicine
Clark BK, Thorp AA, Winkler EA, Gardiner PA, Healy GN, Owen N, Dunstan DW. Validity of self-reported measures of workplace sitting time and breaks in sitting time. Med Sci Sports Exerc. 2011 Oct;43(10):1907-12.

PURPOSE: To understand the prevalence and potential health effect of prolonged workplace sedentary (sitting) time, valid measures are required. Here, we examined the criterion validity of a brief self-reported measure of workplace sitting time and breaks in sitting time.METHODS: An interviewer-administered questionnaire was used to assess workplace sitting time (h·d(-1)) and breaks from sitting per hour at work in a convenience sample of 121 full-time workers (36% men, mean age = 37 yr, 53% office based). These self-reported measures were compared with accelerometer-derived sedentary time (hours per day, <100 counts per minute) and breaks per sedentary hour (number of times, ?100 counts per minute) during work hours.RESULTS: Self-reported sitting time was significantly correlated with accelerometer-derived sedentary time (Pearson r = 0.39, 95% confidence interval = 0.22-0.53), with an average sitting time 0.45 h·d(-1) higher than average sedentary time. Bland-Altman plots and regression analysis showed positive associations between the difference in sitting and sedentary time and the average of sitting and sedentary time (mean difference = -2.75 h + 0.47 × average sitting and sedentary time; limits of agreement = ±2.25 h·d(-1)). The correlation of self-reported breaks per sitting hour with accelerometer-derived breaks per sedentary hour was also statistically significant (Spearman rs = 0.26, 95% confidence interval = 0.11-0.44).CONCLUSIONS: This study is the first to examine the criterion validity of an interviewer-administered questionnaire measure of workplace sitting time and breaks in sitting time using objective criterion measures. The workplace sitting measure has acceptable properties for use in observational studies concerned with sedentary behavior in groups of workers; however, the wide limits of agreement suggest caution in estimating individuals’ sitting time with high precision. Using self-reported measures to capture patterns of workplace sitting (such as breaks in sitting time) requires further development.
Cotten, E. & Prapavessis, H. Increasing nonsedentary behaviors in university students using text messages: Randomized control trial. Cotten, E., & Prapavessis, H (2016). Increasing nonsedentary behaviors in university students using text messages: Randomized control trial. Journal of Medical Internet Research-mHealth and uHealth. 4(3); e99. Doi:10.2196/mhealth.5411

[No abstract available.]
Danielsen YS, Júlíusson PB, Nordhus IH, Kleiven M, Meltzer HM, Olsson SJ, Pallesen S. The relationship between life-style and cardio-metabolic risk indicators in children: the importance of screen time. Acta Paediatr. 2011 Feb;100(2):253-9. doi: 10.1111/j.1651-2227.2010.02098.x. Epub 2010 Dec 15.

AIMS: To examine differences between children with obesity and normal weight children (aged 7-13 years) in terms of physical activity, screen time, food intake and blood parameters indicative of cardio-metabolic risk. Further, to explore the relationship between physical activity, screen time and food intake with cardio-metabolic parameters.METHODS: Forty-three children with obesity were compared with 43 normal weight peers. Physical activity was monitored by accelerometers and screen time and food intake by diaries. Blood parameters indicative of cardio-metabolic risk were analysed.RESULTS: The group of children with obesity had significantly less vigorous activity (p = 0.013), more daily screen time (p = 0.004) and consumed more fat (p = 0.04) than the group of normal weight children. The former group also demonstrated higher values of triglycerides (p = 0.001), HbA1c (p = 0.009), C-peptide (p = 0.001), had a higher HOMA-R score (p = 0.001), and lower levels of HDL (p = 0.001). After controlling for weight category, regression analyses revealed that screen time was significantly and positively related to the HOMA-R score and C-peptide levels independent of physical activity and intake of fat and sugar.CONCLUSIONS: The results indicate that screen time is an important behavioural factor related to obesity and cardio-metabolic risk indicators in children.© 2010 The Author(s)/Acta Paediatrica © 2010 Foundation Acta Paediatrica.
de Jong E, Visscher TL, Hirasing RA, Heymans MW, Seidell JC, Renders CM. Association between TV viewing, computer use and overweight, determinants and competing activities of screen time in 4- to 13-year-old children. Int J Obes (Lond). 2011 Dec 13. doi: 10.1038/ijo.2011.244. [Epub ahead of print]

OBJECTIVE: TV viewing and computer use is associated with childhood overweight, but it remains unclear as to how these behaviours could best be targeted. The aim of this study was to determine to what extent the association between TV viewing, computer use and overweight is explained by other determinants of overweight, to find determinants of TV viewing and computer use in the home environment and to investigate competing activities.METHOD: A cross-sectional study was carried out among 4072 children aged 4-13 years in the city of Zwolle, the Netherlands. Data collection consisted of measured height, weight and waist circumference, and a parental questionnaire on socio-demographic characteristics, child’s nutrition, physical activity (PA) and sedentary behaviour. Associations were studied with logistic regression analyses, for older and younger children, boys and girls separately.RESULTS: The odds ratio (OR) of being overweight was 1.70 (95% confidence interval (CI): 1.07-2.72) for viewing TV >1.5?h among 4- to 8-year-old children adjusted for all potential confounders. Computer use was not significantly associated with overweight. Determinants of TV viewing were as follows: having >2 TVs in the household (OR: 2.38; 95% CI: 1.66-3.41), a TV in the child’s bedroom and not having rules on TV viewing. TV viewing and computer use were both associated with shorter sleep duration and not with less PA.CONCLUSION: Association between TV viewing and overweight is not explained by socio-demographic variables, drinking sugared drinks and eating snacks. Factors in the home environment influence children’s TV viewing. Parents have a central role as they determine the number of TVs, rules and also their children’s bedtime. Therefore, interventions to reduce screen time should support parents in making home environmental changes, especially when the children are young.International Journal of Obesity advance online publication, 13 December 2011; doi:10.1038/ijo.2011.244.
Donahoo WT, Levine JA, Melanson EL. Variability in energy expenditure and its components. Curr Opin Clin Nutr Metab Care. 2004 Nov;7(6):599-605.

PURPOSE OF REVIEW: To review factors contributing to variation in total daily energy expenditure and its primary components: (1) resting metabolic rate; (2) diet-induced thermogenesis; and (3) activity thermogenesis, including exercise energy expenditure and nonexercise activity. For each component, the expected magnitude of intra-individual variability is also considered. We also reviewed studies that quantified the variability in 24 h energy expenditure.RECENT FINDINGS: In humans, the coefficient of variation in the components of total daily energy expenditure is around 5-8% for resting metabolic rate, 1-2% for exercise energy expenditure, and around 20% for diet-induced thermogenesis. The coefficient of variance for 24 h energy expenditure measured using a room calorimeter for resting metabolic rate is around 5-10%. Thus, these measures are all rather reproducible. Total daily energy expenditure varies several-fold in humans, not due to variation in resting metabolic rate, diet-induced thermogenesis, or exercise thermogenesis, but rather, due to variations in nonexercise activity. A variety of factors impact nonexercise activity, including occupation, environment, education, genetics, age, gender, and body composition, but little is known about the magnitude of effect.SUMMARY: Resting metabolic rate, diet-induced thermogenesis, exercise energy expenditure, and 24 h energy expenditure are highly reproducible. Coefficient of variation is smallest for exercise energy expenditure, followed by resting metabolic rate, 24 h energy expenditure, and diet-induced thermogenesis. There is considerable variability in total daily energy expenditure, largely due to variations in nonexercise activity. Although the factors that impact upon nonexercise activity are understood, their contribution to variation in total daily energy expenditure is unclear.
Dunlop DD1, Song J, Arnston EK, Semanik PA, Lee J, Chang RW, Hootman JM. Sedentary time in US older adults associated with disability in activities of daily living independent of physical activity. J Phys Act Health. 2015 Jan;12(1):93-101. doi: 10.1123/jpah.2013-0311. Epub 2014 Feb 5.

BACKGROUND: The harmful relationship of sedentary behavior to health may reflect an exchange of sedentary activity for moderate-to-vigorous physical activity (MVPA), or sedentary behavior may be a separate risk factor. We examined whether time spent in sedentary behavior is related to disability in activities of daily living (ADL), independent of time spent in MVPA in older adults.METHODS: The nationally representative 2003-2006 National Health and Nutrition Examinations Surveys (NHANES) included 2286 adults aged 60 years and older in whom physical activity was assessed by accelerometer. The association between ADL task disability and the daily percentage of sedentary time was evaluated by multiple logistic regression.RESULTS: These adults on average spent 9h/d being sedentary during waking hours and 4.5% reported ADL disability. The odds of ADL disability were 46% greater (odds ratio, 1.46; 95% confidence interval, 1.07-1.98) for each daily hour spent in sedentary behavior, adjusted for MVPA and socioeconomic and health factors.CONCLUSION: These US national data show a strong relationship between greater time spent in sedentary behavior and the presence of ADL disability, independent of time spent in moderate or vigorous activity. These findings support programs encouraging older adults to decrease sedentary behavior regardless of their engagement in moderate or vigorous activity.
Dunstan DW, Barr EL, Healy GN, Salmon J, Shaw JE, Balkau B, Magliano DJ, Cameron AJ, Zimmet PZ, Owen N. Television viewing time and mortality: the Australian Diabetes, Obesity and Lifestyle Study (AusDiab). Circulation. 2010 Jan 26;121(3):384-91. Epub 2010 Jan 11.

BACKGROUND: Television viewing time, the predominant leisure-time sedentary behavior, is associated with biomarkers of cardiometabolic risk, but its relationship with mortality has not been studied. We examined the associations of prolonged television viewing time with all-cause, cardiovascular disease (CVD), cancer, and non-CVD/noncancer mortality in Australian adults.METHODS AND RESULTS: Television viewing time in relation to subsequent all-cause, CVD, and cancer mortality (median follow-up, 6.6 years) was examined among 8800 adults > or =25 years of age in the Australian Diabetes, Obesity and Lifestyle Study (AusDiab). During 58 087 person-years of follow-up, there were 284 deaths (87 CVD deaths, 125 cancer deaths). After adjustment for age, sex, waist circumference, and exercise, the hazard ratios for each 1-hour increment in television viewing time per day were 1.11 (95% confidence interval [CI], 1.03 to 1.20) for all-cause mortality, 1.18 (95% CI, 1.03 to 1.35) for CVD mortality, and 1.09 (95% CI, 0.96 to 1.23) for cancer mortality. Compared with a television viewing time of <2 h/d, the fully adjusted hazard ratios for all-cause mortality were 1.13 (95% CI, 0.87 to 1.36) for > or =2 to <4 h/d and 1.46 (95% CI, 1.04 to 2.05) for > or =4 h/d. For CVD mortality, corresponding hazard ratios were 1.19 (95% CI, 0.72 to 1.99) and 1.80 (95% CI, 1.00 to 3.25). The associations with both cancer mortality and non-CVD/noncancer mortality were not significant.CONCLUSIONS: Television viewing time was associated with increased risk of all-cause and CVD mortality. In addition to the promotion of exercise, chronic disease prevention strategies could focus on reducing sitting time, particularly prolonged television viewing.Comment inMed Klin (Munich). 2010 Jun;105(6):447-9. Circulation. 2010 Sep 28;122(13):e471; author reply e473. Circulation. 2010 Sep 28;122(13):e472; author reply e473.
Dunstan DW, Kingwell BA, Larsen R, Healy GN, Cerin E, Hamilton MT, Shaw JE, Bertovic DA, Zimmet PZ, Salmon J, Owen N. Breaking Up Prolonged Sitting Reduces Postprandial Glucose and Insulin Responses. Diabetes Care. 2012 Feb 28. [Epub ahead of print]

OBJECTIVE: Observational studies show breaking up prolonged sitting has beneficial associations with cardiometabolic risk markers, but intervention studies are required to investigate causality. We examined the acute effects on postprandial glucose and insulin levels of uninterrupted sitting compared with sitting interrupted by brief bouts of light- or moderate-intensity walking.RESEARCH DESIGN AND METHODS: Overweight/obese adults (n = 19), aged 45-65 years, were recruited for a randomized three-period, three-treatment acute crossover trial: 1) uninterrupted sitting; 2) seated with 2-min bouts of light-intensity walking every 20 min; and 3) seated with 2-min bouts of moderate-intensity walking every 20 min. A standardized test drink was provided after an initial 2-h period of uninterrupted sitting. The positive incremental area under curves (iAUC) for glucose and insulin (mean [95% CI]) for the 5 h after the test drink (75 g glucose, 50 g fat) were calculated for the respective treatments.RESULTS: The glucose iAUC (mmol/L) ? h after both activity-break conditions was reduced (light: 5.2 [4.1-6.6]; moderate: 4.9 [3.8-6.1]; both P < 0.01) compared with uninterrupted sitting (6.9 [5.5-8.7]). Insulin iAUC (pmol/L) ? h was also reduced with both activity-break conditions (light: 633.6 [552.4-727.1]; moderate: 637.6 [555.5-731.9], P < 0.0001) compared with uninterrupted sitting (828.6 [722.0-950.9]).CONCLUSIONS: Interrupting sitting time with short bouts of light- or moderate-intensity walking lowers postprandial glucose and insulin levels in overweight/obese adults. This may improve glucose metabolism and potentially be an important public health and clinical intervention strategy for reducing cardiovascular risk.
Dunstan DW, Thorp AA, Healy GN. Prolonged sitting: is it a distinct coronary heart disease risk factor? Curr Opin Cardiol. 2011 Jul 21. [Epub ahead of print]

PURPOSE OF REVIEW: Prolonged sitting (sedentary behavior) has deleterious cardiovascular and metabolic correlates; however, little is known about the associations of too much sitting with all-cause and cardiovascular mortality risk. In addition to the adverse effects of total sitting time, the manner in which it is accumulated has also been postulated to be important for cardiovascular health.RECENT FINDINGS: We describe recent evidence from several research papers published in the last 12-18 months, showing deleterious relationships of sedentary behavior with mortality outcomes. We also explore emerging findings on breaking up sedentary time and its potential beneficial impact on cardiovascular health.SUMMARY: Consistent independent associations have been observed between sitting time/sedentary behaviors and elevated all-cause and cardiovascular disease mortality risk. Generally, these associations have persisted following adjustment for physical activity. Furthermore, total sedentary time (measured objectively via accelerometer) is detrimentally associated with several cardiovascular risk factors, whereas breaking up sedentary time (independent of total sedentary time and moderate-to-vigorous intensity activity) is beneficially associated. This evidence provides further support to the importance of avoiding prolonged, uninterrupted periods of sitting time for cardiovascular health. However, further evidence from intervention trials is required to establish the causal pathways.
Duvivier BM, Schaper NC, Bremers MA, van Crombrugge G, Menheere PP, Kars M, Savelberg HH. Minimal intensity physical activity (standing and walking) of longer duration improves insulin action and plasma lipids more than shorter periods of moderate to vigorous exercise (cycling) in sedentary subjects when energy expenditure is comparable. PLoS One. 2013;8(2):e55542. doi: 10.1371/journal.pone.0055542. Epub 2013 Feb 13.

BACKGROUND: Epidemiological studies suggest that excessive sitting time is associated with increased health risk, independent of the performance of exercise. We hypothesized that a daily bout of exercise cannot compensate the negative effects of inactivity during the rest of the day on insulin sensitivity and plasma lipids.METHODOLOGY/PRINCIPAL FINDINGS: Eighteen healthy subjects, age 21±2 year, BMI 22.6±2.6 kgm(-2) followed randomly three physical activity regimes for four days. Participants were instructed to sit 14 hr/day (sitting regime); to sit 13 hr/day and to substitute 1 hr of sitting with vigorous exercise 1 hr (exercise regime); to substitute 6 hrs sitting with 4 hr walking and 2 hr standing (minimal intensity physical activity (PA) regime). The sitting and exercise regime had comparable numbers of sitting hours; the exercise and minimal intensity PA regime had the same daily energy expenditure. PA was assessed continuously by an activity monitor (ActivPAL) and a diary. Measurements of insulin sensitivity (oral glucose tolerance test, OGTT) and plasma lipids were performed in the fasting state, the morning after the 4 days of each regime. In the sitting regime, daily energy expenditure was about 500 kcal lower than in both other regimes. Area under the curve for insulin during OGTT was significantly lower after the minimal intensity PA regime compared to both sitting and exercise regimes 6727.3±4329.4 vs 7752.0±3014.4 and 8320.4±5383.7 mU•min/ml, respectively. Triglycerides, non-HDL cholesterol and apolipoprotein B plasma levels improved significantly in the minimal intensity PA regime compared to sitting and showed non-significant trends for improvement compared to exercise.CONCLUSIONS: One hour of daily physical exercise cannot compensate the negative effects of inactivity on insulin level and plasma lipids if the rest of the day is spent sitting. Reducing inactivity by increasing the time spent walking/standing is more effective than one hour of physical exercise, when energy expenditure is kept constant.
Edelson LR, Mathias KC, Fulgoni VL 3rd, Karagounis LG Screen-based sedentary behavior and associations with functional strength in 6-15 year-old children in the United States. BMC Public Health. 2016 Feb 4;16(1):116. doi: 10.1186/s12889-016-2791-9.

BACKGROUND: Physical strength is associated with improved health outcomes in children. Heavier children tend to have lower functional strength and mobility. Physical activity can increase children’s strength, but it is unknown how different types of electronic media use impact physical strength. METHODS: Data from the NHANES National Youth Fitness Survey (NNYFS) from children ages 6-15 were analyzed in this study. Regression models were conducted to determine if screen-based sedentary behaviors (television viewing time, computer/video game time) were associated with strength measures (grip, leg extensions, modified pull-ups, plank) while controlling for potential confounders including child age, sex, BMI z-score, and days per week with 60+ minutes of physical activity. Grip strength and leg extensions divided by body weight were analyzed to provide measures of relative strength together with pull-ups and plank, which require lifting the body. RESULTS: The results from the regression models showed the hypothesized inverse association between TV time and all strength measures. Computer time was only significantly inversely associated with the ability to do one or more pull-ups. CONCLUSIONS: This study shows that television viewing, but not computer/videogames, is inversely associated with measures of child strength while controlling for child characteristics and physical activity. These findings suggest that “screen time” may not be a unified construct with respect to strength outcomes and that further exploration of the potential benefits of reducing television time on children’s strength and related mobility is needed.
Ekelund U, Brage S, Froberg K, Harro M, Anderssen SA, Sardinha LB, Riddoch C, Andersen LB. TV viewing and physical activity are independently associated with metabolic risk in children: the European Youth Heart Study. PLoS Med. 2006 Dec;3(12):e488.

BACKGROUND: TV viewing has been linked to metabolic-risk factors in youth. However, it is unclear whether this association is independent of physical activity (PA) and obesity.METHODS AND FINDINGS: We did a population-based, cross-sectional study in 9- to 10-y-old and 15- to 16-y-old boys and girls from three regions in Europe (n = 1,921). We examined the independent associations between TV viewing, PA measured by accelerometry, and metabolic-risk factors (body fatness, blood pressure, fasting triglycerides, inverted high-density lipoprotein (HDL) cholesterol, glucose, and insulin levels). Clustered metabolic risk was expressed as a continuously distributed score calculated as the average of the standardized values of the six subcomponents. There was a positive association between TV viewing and adiposity (p = 0.021). However, after adjustment for PA, gender, age group, study location, sexual maturity, smoking status, birth weight, and parental socio-economic status, the association of TV viewing with clustered metabolic risk was no longer significant (p = 0.053). PA was independently and inversely associated with systolic and diastolic blood pressure, fasting glucose, insulin (all p < 0.01), and triglycerides (p = 0.02). PA was also significantly and inversely associated with the clustered risk score (p < 0.0001), independently of obesity and other confounding factors.CONCLUSIONS: TV viewing and PA may be separate entities and differently associated with adiposity and metabolic risk. The association between TV viewing and clustered metabolic risk is mediated by adiposity, whereas PA is associated with individual and clustered metabolic-risk indicators independently of obesity. Thus, preventive action against metabolic risk in children may need to target TV viewing and PA separately.Comment inPLoS Med. 2006 Dec;3(12):e481.
El Achhab Y, El Ammari A, El Kazdouh H, Najdi A, Berraho M, Tachfouti N, Lamri D, El Fakir S, Nejjari C. Health risk behaviours amongst school adolescents: protocol for a mixed methods study. El Achhab Y, El Ammari A, El Kazdouh H, Najdi A, Berraho M, Tachfouti N, Lamri D, El Fakir S, Nejjari C. Health risk behaviours amongst school adolescents: protocol for a mixed methods study. BMC Public Health. 2016 Nov 29;16(1):1209.

BACKGROUND: Determining risky behaviours of adolescents provides valuable information for designing appropriate intervention programmes for advancing adolescent's health. However, these behaviours are not fully addressed by researchers in a comprehensive approach. We report the protocol of a mixed methods study designed to investigate the health risk behaviours of Moroccan adolescents with the goal of identifying suitable strategies to address their health concerns. METHODS: We used a sequential two-phase explanatory mixed method study design. The approach begins with the collection of quantitative data, followed by the collection of qualitative data to explain and enrich the quantitative findings. In the first phase, the global school-based student health survey (GSHS) was administered to 800 students who were between 14 and 19 years of age. The second phase engaged adolescents, parents and teachers in focus groups and assessed education documents to explore the level of coverage of health education in the programme learnt in the middle school. To obtain opinions about strategies to reduce Moroccan adolescents' health risk behaviours, a nominal group technique will be used. DISCUSSION: The findings of this mixed methods sequential explanatory study provide insights into the risk behaviours that need to be considered if intervention programmes and preventive strategies are to be designed to promote adolescent's health in the Moroccan school.
Endrighi R, Steptoe A, Hamer M. The effect of experimentally induced sedentariness on mood and psychobiological responses to mental stress. Br J Psychiatry. 2015 Aug 20. pii: bjp.bp.114.150755. [Epub ahead of print]

BackgroundEvidence suggests a link between sedentary behaviours and depressive symptoms. Mechanisms underlying this relationship are not understood, but inflammatory processes may be involved. Autonomic and inflammatory responses to stress may be heightened in sedentary individuals contributing to risk, but no study has experimentally investigated this.AimTo examine the effect of sedentary time on mood and stress responses using an experimental design.MethodForty-three individuals were assigned to a free-living sedentary condition and to a control condition (usual activity) in a cross-over, randomised fashion and were tested in a psychophysiology laboratory after spending 2 weeks in each condition. Participants completed mood questionnaires (General Health Questionnaire and Profile of Mood States) and wore a motion sensor for 4 weeks.ResultsSedentary time increased by an average of 32 min/day (P = 0.01) during the experimental condition compared with control. Being sedentary resulted in increases in negative mood independent of changes in moderate to vigorous physical activity (?GHQ = 6.23, ?POMS = 2.80). Mood disturbances were associated with greater stress-induced inflammatory interleukin-6 (IL-6) responses (? = 0.37).ConclusionTwo weeks of exposure to greater free-living sedentary time resulted in mood disturbances independent of reduction in physical activity. Stress-induced IL-6 responses were associated with changes in mood.© The Royal College of Psychiatrists 2015.
Epstein LH, Roemmich JN, Robinson JL, Paluch RA, Winiewicz DD, Fuerch JH, Robinson TN. A randomized trial of the effects of reducing television viewing and computer use on body mass index in young children. Arch Pediatr Adolesc Med. 2008 Mar;162(3):239-45.

OBJECTIVE: To assess the effects of reducing television viewing and computer use on children’s body mass index (BMI) as a risk factor for the development of overweight in young children.DESIGN: Randomized controlled clinical trial.SETTING: University children’s hospital.PARTICIPANTS: Seventy children aged 4 to 7 years whose BMI was at or above the 75th BMI percentile for age and sex.INTERVENTIONS: Children were randomized to an intervention to reduce their television viewing and computer use by 50% vs a monitoring control group that did not reduce television viewing or computer use.MAIN OUTCOME MEASURES: Age- and sex-standardized BMI (zBMI), television viewing, energy intake, and physical activity were monitored every 6 months during 2 years.RESULTS: Children randomized to the intervention group showed greater reductions in targeted sedentary behavior (P < .001), zBMI (P < .05), and energy intake (P < .05) compared with the monitoring control group. Socioeconomic status moderated zBMI change (P = .01), with the experimental intervention working better among families of low socioeconomic status. Changes in targeted sedentary behavior mediated changes in zBMI (P < .05). The change in television viewing was related to the change in energy intake (P < .001) but not to the change in physical activity (P =.37).CONCLUSIONS: Reducing television viewing and computer use may have an important role in preventing obesity and in lowering BMI in young children, and these changes may be related more to changes in energy intake than to changes in physical activity.Comment inArch Pediatr Adolesc Med. 2008 Mar;162(3):283-4. Arch Pediatr Adolesc Med. 2008 Sep;162(9):899; author reply 899-900.
Ford ES, Li C, Zhao G, Pearson WS, Tsai J, Churilla JR. Sedentary behavior, physical activity, and concentrations of insulin among US adults. Metabolism. 2010 Sep;59(9):1268-75. Epub 2010 Jan 13.

Time spent watching television has been linked to obesity, metabolic syndrome, and diabetes, all conditions characterized to some degree by hyperinsulinemia and insulin resistance. However, limited evidence relates screen time (watching television or using a computer) directly to concentrations of insulin. We examined the cross-sectional associations between time spent watching television or using a computer, physical activity, and serum concentrations of insulin using data from 2800 participants aged at least 20 years of the 2003-2006 National Health and Nutrition Examination Survey. The amount of time spent watching television and using a computer as well as physical activity was self-reported. The unadjusted geometric mean concentration of insulin increased from 6.2 microU/mL among participants who did not watch television to 10.0 microU/mL among those who watched television for 5 or more hours per day (P = .001). After adjustment for age, sex, race or ethnicity, educational status, concentration of cotinine, alcohol intake, physical activity, waist circumference, and body mass index using multiple linear regression analysis, the log-transformed concentrations of insulin were significantly and positively associated with time spent watching television (P = < .001). Reported time spent using a computer was significantly associated with log-transformed concentrations of insulin before but not after accounting for waist circumference and body mass index. Leisure-time physical activity but not transportation or household physical activity was significantly and inversely associated with log-transformed concentrations of insulin. Sedentary behavior, particularly the amount of time spent watching television, may be an important modifiable determinant of concentrations of insulin.Published by Elsevier Inc.
Gardiner PA, Clark BK, Healy GN, Eakin EG, Winkler EA, Owen N. Measuring older adults' sedentary time: reliability, validity, and responsiveness. Med Sci Sports Exerc. 2011 Nov;43(11):2127-33.

PURPOSE: : With evidence that prolonged sitting has deleterious health consequences, decreasing sedentary time is a potentially important preventive health target. High-quality measures, particularly for use with older adults, who are the most sedentary population group, are needed to evaluate the effect of sedentary behavior interventions. We examined the reliability, validity, and responsiveness to change of a self-report sedentary behavior questionnaire that assessed time spent in behaviors common among older adults: watching television, computer use, reading, socializing, transport and hobbies, and a summary measure (total sedentary time).METHODS: : In the context of a sedentary behavior intervention, nonworking older adults (n = 48, age = 73 ± 8 yr (mean ± SD)) completed the questionnaire on three occasions during a 2-wk period (7 d between administrations) and wore an accelerometer (ActiGraph model GT1M) for two periods of 6 d. Test-retest reliability (for the individual items and the summary measure) and validity (self-reported total sedentary time compared with accelerometer-derived sedentary time) were assessed during the 1-wk preintervention period, using Spearman (?) correlations and 95% confidence intervals (CI). Responsiveness to change after the intervention was assessed using the responsiveness statistic (RS).RESULTS: : Test-retest reliability was excellent for television viewing time (? (95% CI) = 0.78 (0.63-0.89)), computer use (? (95% CI) = 0.90 (0.83-0.94)), and reading (? (95% CI) = 0.77 (0.62-0.86)); acceptable for hobbies (? (95% CI) = 0.61 (0.39-0.76)); and poor for socializing and transport (? < 0.45). Total sedentary time had acceptable test-retest reliability (? (95% CI) = 0.52 (0.27-0.70)) and validity (? (95% CI) = 0.30 (0.02-0.54)). Self-report total sedentary time was similarly responsive to change (RS = 0.47) as accelerometer-derived sedentary time (RS = 0.39).CONCLUSIONS: : The summary measure of total sedentary time has good repeatability and modest validity and is sufficiently responsive to change suggesting that it is suitable for use in interventions with older adults.
Gardiner PA, Eakin EG, Healy GN, Owen N. Feasibility of reducing older adults' sedentary time. Am J Prev Med. 2011 Aug;41(2):174-7.

BACKGROUND: Sedentary time (too much sitting, as distinct from lack of exercise) is a prevalent risk to health among older adults.PURPOSE: Examine the feasibility of an intervention to reduce and break up sedentary time in older adults.DESIGN: A pre-experimental (pre-post) study.SETTING/PARTICIPANTS: A total of 59 participants aged ?60 years from Brisbane, Australia. Data were collected between May and December 2009 and analyzed in 2010.INTERVENTION: One face-to-face goal-setting consultation and one individually tailored mailing providing feedback on accelerometer-derived sedentary time, grounded in social cognitive theory and behavioral choice theory.MAIN OUTCOME MEASURES: Program reach and retention; changes in accelerometer-derived sedentary time, light-intensity physical activity (LIPA), and moderate-to-vigorous-intensity physical activity (MVPA) (assessed over 6 days in pre- and post-intervention periods); and participant satisfaction.RESULTS: Reach was 87.5% of those screened and eligible; retention was 100%. From pre- to post-intervention, participants decreased their sedentary time [-3.2% (95% CI= -4.18, -2.14), p<0.001], increased their breaks in sedentary time per day [4.0 (1.48, 6.52), p=0.003], and increased their LIPA [2.2% (1.40, 2.99), p<0.001] and MVPA [1.0% (0.55, 1.38), p<0.001]. Significantly greater reductions in sedentary time were made after 10:00am, with significantly greater number of breaks occurring between 7:00pm and 9:00pm. Participants reported high satisfaction with the program (median 9/10).CONCLUSIONS: Sedentary time in older adults can be reduced following a brief intervention based on goal setting and behavioral self-monitoring.Copyright © 2011 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.
Gardiner PA, Healy GN, Eakin EG, Clark BK, Dunstan DW, Shaw JE, Zimmet PZ, Owen N. Associations between television viewing time and overall sitting time with the metabolic syndrome in older men and women: the Australian Diabetes, Obesity and Lifestyle study. J Am Geriatr Soc. 2011 May;59(5):788-96. doi: 10.1111/j.1532-5415.2011.03390.x.

OBJECTIVES: To examine associations between self-reported television (TV) viewing time and overall sitting time with the metabolic syndrome and its components.DESIGN: Cross-sectional.SETTING: Population-based sample of older men and women living in Australia.PARTICIPANTS: One thousand nine hundred fifty-eight participants from the Australian Diabetes, Obesity and Lifestyle (AusDiab) study (aged ? 60, mean age 69, 54% women).MEASUREMENTS: Self-reported television viewing time and overall sitting time were collected using an interviewer-administered questionnaire. The metabolic syndrome was defined according to the revised International Diabetes Federation criteria.RESULTS: Compared with those in the lowest quartile, the odds ratios (ORs) of the metabolic syndrome in the highest quartile of television viewing time were 1.42 (95% confidence interval (CI)=0.93-2.15) for men and 1.42 (95% CI=1.01-2.01) for women and in the highest quartile of overall sitting time were 1.57 (95% CI=1.02-2.41) for men and 1.56 (95% CI=1.09-2.24) for women. Television viewing time was associated with lower high-density lipoprotein cholesterol (HDL-C) levels and glucose intolerance in women. Overall sitting time was detrimentally associated with greater risk of high triglyceride levels in men and women, abdominal obesity in women, and low HDL-C levels in men. All models were adjusted for age, education, physical activity, self-rated health, employment, diet, smoking, and alcohol intake and for hormone replacement therapy and estrogen use in women.CONCLUSION: For older adults, high levels of sedentary behavior were associated with greater prevalence of the metabolic syndrome; reducing prolonged overall sitting time may be a feasible way to improve metabolic health.© 2011, Copyright the Authors. Journal compilation © 2011, The American Geriatrics Society.
Gaston, A., De Jesus, S., Markland, D., & Prapavessis, H. I sit because I have fun when I do so! Using self-determination theory to understand sedentary behavior motivation. Gaston, A., De Jesus, S., Markland, D., & Prapavessis, H (2016). I sit because I have fun when I do so! Using self-determination theory to understand sedentary behavior motivation. Health Psychology and Behavioral Medicine, 4(1), 138-154. doi:10.1080/21642850.2016.1170605

[No abstract available.]
Gilson ND, Suppini A, Ryde GC, Brown HE, Brown WJ. Does the use of standing 'hot' desks change sedentary work time in an open plan office? Prev Med. 2011 Oct 26. [Epub ahead of print]

OBJECTIVE: This study assessed the use of standing ‘hot’ desks in an open plan office and their impact on sedentary work time.METHOD: Australian employees (n=11; 46.9 [9.8] years; BMI 25.9 [3.5kg/m(2)]) wore an armband accelerometer for two consecutive working weeks (November-December 2010). In the second week, employees were encouraged to use a pod of four standing ‘hot’ desks to stand and work as often as possible. Desk use was recorded using time logs. The percentages of daily work time spent in sedentary (<1.6 METs), light (1.6-3.0 METs) and moderate+ (>3 METs) intensity categories were calculated for each week, relative to the total daily time at work. Paired sample t tests were used to compare weekly differences.RESULTS: Employees spent 8:09±0:31h/day at work and ‘hot’ desk use ranged from zero to 9:35h for the week. There were no significant changes in mean time spent in sedentary (difference of -0.1%), light (difference of 0.8%) and moderate+ (-0.7%) intensity categories. However, individual changes in sedentary work time ranged from -5.9 to 6.4%.CONCLUSIONS: Volitional use of standing ‘hot’ desks varied and while individual changes were apparent, desk use did not alter overall sedentary work time in this sample.Copyright © 2011. Published by Elsevier Inc.
Goldfield GS, Kenny GP, Hadjiyannakis S, Phillips P, Alberga AS, Saunders TJ, Tremblay MS, Malcolm J, Prud'homme D, Gougeon R, Sigal RJ. Video game playing is independently associated with blood pressure and lipids in overweight and obese adolescents. PLoS One. 2011;6(11):e26643. Epub 2011 Nov 1.

OBJECTIVE: To examine the association between duration and type of screen time (TV, video games, computer time) and blood pressure (BP) and lipids in overweight and obese adolescents.DESIGN: This is a cross-sectional study of 282 overweight or obese adolescents aged 14-18 years (86 males, 196 females) assessed at baseline prior to beginning a lifestyle intervention study for weight control. Sedentary behaviours, defined as hours per day spent watching TV, playing video games, recreational computer use and total screen time were measured by self-report. We examined the associations between sedentary behaviours and BP and lipids using multiple linear regression.RESULTS: Seated video gaming was the only sedentary behaviour associated with elevated BP and lipids before and after adjustment for age, sex, pubertal stage, parental education, body mass index (BMI), caloric intake, percent intake in dietary fat, physical activity (PA) duration, and PA intensity. Specifically, video gaming remained positively associated with systolic BP (adjusted r?=?0.13, ??=?1.1, p<0.05) and total cholesterol/HDL ratio (adjusted r?=?0.12, ??=?0.14, p<0.05).CONCLUSIONS: Playing video games was the only form of sedentary behaviour that was independently associated with increased BP and lipids. Our findings provide support for reducing time spent playing seated video games as a possible means to promote health and prevent the incidence of cardiovascular disease (CVD) risk factors in this high risk group of overweight and obese adolescents. Future research is needed to first replicate these findings and subsequently aim to elucidate the mechanisms linking seated video gaming and elevated BP and lipids in this high risk population.TRIAL REGISTRATION: NCT00195858.
Gorely T, Marshall SJ, Biddle SJ, Cameron N. Patterns of sedentary behaviour and physical activity among adolescents in the United Kingdom: Project STIL. J Behav Med. 2007 Dec;30(6):521-31. Epub 2007 Aug 22.

The purpose of this study was to use ecological momentary assessment to investigate the patterning of physical activity and sedentary behaviours in UK adolescents and to examine if different lifestyle groups differ on key explanatory variables. A total of 1,371 (38% boys, mean age 14.7 years) adolescents completed diaries every 15 min for 3 weekdays outside of school hours and 1 weekend day. Cluster analysis yielded five-cluster solutions for both boys and girls to explain the grouping of sedentary behaviours and physical activity. The clusters demonstrated that adolescents engage in many leisure time behaviours but have one activity that predominates. Active adolescents spend more time outside and more time with their friends. Few demographic and environmental variables distinguished between clusters. The findings suggest a potential need for different behavioural targets in interventions to reduce sedentary behaviour in sub groups of the adolescent population. Further research is required to examine the modifiable determinants of different sedentary lifestyles among young people.
Gorely T, Marshall SJ, Biddle SJ, Cameron N. The prevalence of leisure time sedentary behaviour and physical activity in adolescent girls: an ecological momentary assessment approach. Int J Pediatr Obes. 2007;2(4):227-34.

STUDY OBJECTIVE: To use ecological momentary assessment to describe how adolescent girls in the United Kingdom spend their leisure time.DESIGN: Cross-sectional, stratified, random sample from secondary schools in 15 regions within the United Kingdom. The data are from a larger study of adolescent lifestyles (Project STIL).PARTICIPANTS: A total of 923 girls with a mean age of 14.7 years (range 12.5-17.6 years). The majority were white-European (88.7%).MAIN RESULTS: Across all behaviours, television viewing occupied the most leisure time on both weekdays and weekend days. The five most time consuming sedentary weekday activities occupied on average 262.9 minutes per weekday and 400 minutes per weekend day. In contrast, only 44.2 minutes was occupied by active transport or sports and exercise per weekday, and 53 minutes per weekend day. Only a minority watched more than 4 hours of TV per day (3.3% on weekdays and 20.7% on weekend days). Computer use is low in this group. Some differences were noted in the means and prevalences between weekend and weekdays, most likely reflecting the greater discretionary time available at the weekend. Few age differences were noted.CONCLUSIONS: Adolescent girls engage in a variety of behaviours that contribute to an overall lifestyle that may be active or sedentary. Effective physical activity promotion strategies must focus on facilitating shifts towards healthy overall patterns of behaviour rather than shifts in any one single behaviour.
Gorely T, Marshall SJ, Biddle SJ. Couch kids: correlates of television viewing among youth. Int J Behav Med. 2004;11(3):152-63.

The purpose of this study was to review the published empirical correlates of television/video viewing among youth (2 to 18 years). A descriptive semi-quantitative review was conducted based on 68 primary studies. Variables consistently associated with TV/video viewing were ethnicity (non-white +), parent income (-), parent education (-), body weight (+), between meal snacking (+), number of parents in the house (-), parents TV viewing habits (+), weekend (+) and having a TV in the bedroom (+). Variables consistently unrelated to TV/video viewing were sex, other indicators of socio-economic status, body fatness, cholesterol levels, aerobic fitness, strength, other indicators of fitness, self-perceptions, emotional support, physical activity, other diet variables, and being an only child. Few modifiable correlates have been identified. Further research should aim to identify modifiable correlates of TV/video viewing if interventions are to be successfully tailored to reduce this aspect of inactivity among youth.
Granados K, Stephens BR, Malin SK, Zderic TW, Hamilton MT, Braun B. Appetite regulation in response to sitting and energy imbalance. The impact of sitting and energy imbalance on appetite and appetite-regulating hormones (acylated ghrelin and leptin) was assessed in response to 1 day of sitting, with and without changes in energy intake. Fourteen men and women completed each of three 24-h conditions: high energy expenditure (standing) with energy balance (STAND), low energy expenditure (sitting) with energy surplus (SIT), and sitting with energy balance (SIT-BAL). Ghrelin, leptin, and appetite were measured in the fasted state and following a standardized meal. In the fasted state, there were no differences among conditions. Following the meal, ghrelin was lower in SIT than in STAND, with no change in appetite. When intake was reduced (SIT-BAL), the decrease in ghrelin when sitting was attenuated, hunger increased, and fullness decreased. SIT led to lower ghrelin concentrations in the men, whereas in the women, leptin increased. SIT-BAL led to an increase in ghrelin in the men but attenuated the leptin response, reduced ghrelin, increased hunger, and decreased fullness in the women. Because a dramatic reduction in energy expenditure was not accompanied by reduced appetite, prolonged sitting may promote excess energy intake, leading to weight gain in both men and women.

Grüsser SM, Thalemann R, Albrecht U, Thalemann CN. [Excessive computer usage in adolescents--results of a psychometric evaluation]. Wien Klin Wochenschr. 2005 Mar;117(5-6):188-95.

Excessive computer and video game playing among children is being critically discussed from a pedagogic and public health point of view. To date, no reliable data for this phenomenon in Germany exists. In the present study, the excessive usage of computer and video games is seen as a rewarding behavior which can, due to learning mechanisms, become a prominent and inadequate strategy for children to cope with negative emotions like frustration, uneasiness and fears. In the survey, 323 children ranging in age from 11 to 14 years were asked about their video game playing behavior. Criteria for excessive computer and video game playing were developed in accordance with the criteria for dependency and pathological gambling (DSM-IV, ICD-10). Data show that 9.3% (N = 30) of the children fulfill all criteria for excessive computer and video game playing. Furthermore, these children differ from their class mates with respect to watching television, communication patterns, the ability to concentrate in school lectures and the preferred strategies coping with negative emotions. In accordance with findings in studies about substance-related addiction, data suggest that excessive computer and video game players use their excessive rewarding behavior specifically as an inadequate stress coping strategy.Comment inWien Klin Wochenschr. 2005 Mar;117(5-6):173-5.
Hamburg NM, McMackin CJ, Huang AL, Shenouda SM, Widlansky ME, Schulz E, Gokce N, Ruderman NB, Keaney JF Jr, Vita JA. Physical inactivity rapidly induces insulin resistance and microvascular dysfunction in healthy volunteers. Arterioscler Thromb Vasc Biol. 2007 Dec;27(12):2650-6. Epub 2007 Oct 11.

OBJECTIVE: Sedentary lifestyle increases the risk of cardiovascular disease and diabetes. Vascular dysfunction contributes to atherogenesis and has been linked to insulin resistance.METHODS AND RESULTS: We measured insulin sensitivity by glucose tolerance test and vascular function by ultrasound and venous occlusion plethysmography in 20 healthy subjects (14 men, 6 women) at baseline and during 5 days of bed rest. Bed rest led to a 67% increase in the insulin response to glucose loading (P<0.001) suggesting increased insulin resistance and produced increases in total cholesterol and triglycerides. Bed rest led to decreased reactive hyperemia in the forearm (1317+/-404 to 1112+/-260 mL/min, P=0.01) and the calf (28.5+/-7.0 to 22.2+/-8.7 mL/min/dL, P=0.003) indicating impaired microvascular function. Bed rest decreased brachial artery diameter and increased systolic blood pressure suggesting increased basal arterial tone. There were no changes in circulating inflammatory markers arguing against systemic inflammation as a mechanism for vascular dysfunction in this setting.CONCLUSIONS: Physical inactivity was associated with the development of insulin resistance, dyslipidemia, increased blood pressure, and impaired microvascular function in healthy volunteers. Our findings may provide insight into the pathogenesis of vascular disease in sedentary individuals and emphasize that even short-term physical inactivity may have adverse metabolic and vascular consequences.
Hamilton MT, Hamilton DG, Zderic TW. Role of low energy expenditure and sitting in obesity, metabolic syndrome, type 2 diabetes, and cardiovascular disease. Diabetes. 2007 Nov;56(11):2655-67. Epub 2007 Sep 7.

It is not uncommon for people to spend one-half of their waking day sitting, with relatively idle muscles. The other half of the day includes the often large volume of nonexercise physical activity. Given the increasing pace of technological change in domestic, community, and workplace environments, modern humans may still not have reached the historical pinnacle of physical inactivity, even in cohorts where people already do not perform exercise. Our purpose here is to examine the role of sedentary behaviors, especially sitting, on mortality, cardiovascular disease, type 2 diabetes, metabolic syndrome risk factors, and obesity. Recent observational epidemiological studies strongly suggest that daily sitting time or low nonexercise activity levels may have a significant direct relationship with each of these medical concerns. There is now a need for studies to differentiate between the potentially unique molecular, physiologic, and clinical effects of too much sitting (inactivity physiology) separate from the responses caused by structured exercise (exercise physiology). In theory, this may be in part because nonexercise activity thermogenesis is generally a much greater component of total energy expenditure than exercise or because any type of brief, yet frequent, muscular contraction throughout the day may be necessary to short-circuit unhealthy molecular signals causing metabolic diseases. One of the first series of controlled laboratory studies providing translational evidence for a molecular reason to maintain high levels of daily low-intensity and intermittent activity came from examinations of the cellular regulation of skeletal muscle lipoprotein lipase (LPL) (a protein important for controlling plasma triglyceride catabolism, HDL cholesterol, and other metabolic risk factors). Experimentally reducing normal spontaneous standing and ambulatory time had a much greater effect on LPL regulation than adding vigorous exercise training on top of the normal level of nonexercise activity. Those studies also found that inactivity initiated unique cellular processes that were qualitatively different from the exercise responses. In summary, there is an emergence of inactivity physiology studies. These are beginning to raise a new concern with potentially major clinical and public health significance: the average nonexercising person may become even more metabolically unfit in the coming years if they sit too much, thereby limiting the normally high volume of intermittent nonexercise physical activity in everyday life. Thus, if the inactivity physiology paradigm is proven to be true, the dire concern for the future may rest with growing numbers of people unaware of the potential insidious dangers of sitting too much and who are not taking advantage of the benefits of maintaining nonexercise activity throughout much of the day.
Hamilton MT, Hamilton DG, Zderic TW. Exercise physiology versus inactivity physiology: an essential concept for understanding lipoprotein lipase regulation. Exerc Sport Sci Rev. 2004 Oct;32(4):161-6.

Some health-related proteins such as lipoprotein lipase may be regulated by qualitatively different processes over the physical activity continuum, sometimes with very high sensitivity to inactivity. The most powerful process known to regulate lipoprotein lipase protein and activity in muscle capillaries may be initiated by inhibitory signals during physical inactivity, independent of changes in lipoprotein lipase messenger RNA.
Hartmann, Lisa Identifying the Common Sedentary Activities/Behaviours, Levels of Physical Activity and Trends Amongst Students

The purpose of this research was to investigate the common sedentary activities and behaviours of students here in the Middle East and across the world, whilst exploring levels of physical activity and trends amongst students. The review of literature concentrated on uncovering research from 2005 to 2015 with the aim of discussing and critically analysing the different author’s points of view. During the review I have drawn on my own teaching experiences gained whilst living in the Middle East. The literature review has highlighted many causes of sedentary behaviour, and addressed the challenges that schools face when tackling the issue of sedentary students. The following factors that were associated with causing students to choose sedentary behaviours were identified amongst the research: health policies and strategies, parental education or influence, PE lessons and school environment (including effects on academic performance, snack, lunchtime breaks, and equipment available), participation in extra-curricular activities (involvement in sports teams, and the upsurge in use of technology), travel to and from school, and living in the UAE. In particular, the important role that schools play in the promotion and encouragement of physical activity, whilst reducing sedentary behaviours. Key words/phrases: Sedentary students, Sedentary behaviours, Physical Education lessons, school health programs, Physical Activity levels, school health policies and procedures.
Hawkes AL, Lynch BM, Owen N, Aitken JF. Lifestyle factors associated concurrently and prospectively with co-morbid cardiovascular disease in a population-based cohort of colorectal cancer survivors. Eur J Cancer. 2011 Jan;47(2):267-76. Epub 2010 Nov 10.

AIMS: To assess self-reported lifetime prevalence of cardiovascular disease (CVD) among colorectal cancer survivors, and examine the cross-sectional and prospective associations of lifestyle factors with co-morbid CVD.METHODS: Colorectal cancer survivors were recruited (n=1966). Data were collected at approximately 5, 12, 24 and 36 months post-diagnosis. Cross-sectional findings included six CVD categories (hypercholesterolaemia, hypertension, diabetes, heart failure, kidney disease and ischaemic heart disease (IHD)) at 5 months post-diagnosis. Longitudinal outcomes included the probability of developing (de novo) co-morbid CVD by 36 months post-diagnosis. Lifestyle factors included body mass index, physical activity, television (TV) viewing, alcohol consumption and smoking.RESULTS: Co-morbid CVD prevalence at 5 months post-diagnosis was 59%, and 16% of participants with no known CVD at the baseline reported de novo CVD by 36 months. Obesity at the baseline predicted de novo hypertension (odds ratio [OR]=2.20, 95% confidence intervals [CI]=1.09, 4.45) and de novo diabetes (OR=6.55, 95% CI=2.19, 19.53). Participants watching >4h of TV/d at the baseline (compared with <2h/d) were more likely to develop ischaemic heart disease by 36 months (OR=5.51, 95% CI=1.86, 16.34).CONCLUSION: Overweight colorectal cancer survivors were more likely to suffer from co-morbid CVD. Interventions focusing on weight management and other modifiable lifestyle factors may reduce functional decline and improve survival.Copyright © 2010 Elsevier Ltd. All rights reserved.
Healy GN, Clark BK, Winkler EA, Gardiner PA, Brown WJ, Matthews CE. Measurement of adults' sedentary time in population-based studies. Am J Prev Med. 2011 Aug;41(2):216-27.

Sedentary time (too much sitting) increasingly is being recognized as a distinct health risk behavior. This paper reviews the reliability and validity of self-reported and device-based sedentary time measures and provides recommendations for their use in population-based studies. The focus is on instruments that have been used in free-living, population-based research in adults. Data from the 2003-2006 National Health and Nutrition Examination Survey are utilized to compare the descriptive epidemiology of sedentary time that arises from the use of different sedentary time measures. A key recommendation from this review is that, wherever possible, population-based monitoring of sedentary time should incorporate both self-reported measures (to capture important domain- and behavior-specific sedentary time information) and device-based measures (to measure both total sedentary time and patterns of sedentary time accumulation).Copyright © 2011 American Journal of Preventive Medicine. All rights reserved.
Healy GN, Dunstan DW, Salmon J, Cerin E, Shaw JE, Zimmet PZ, Owen N. Objectively measured light-intensity physical activity is independently associated with 2-h plasma glucose. Diabetes Care. 2007 Jun;30(6):1384-9. Epub 2007 May 1.

OBJECTIVE: We examined the associations of objectively measured sedentary time, light-intensity physical activity, and moderate- to vigorous-intensity activity with fasting and 2-h postchallenge plasma glucose in Australian adults.RESEARCH DESIGN AND METHODS: A total of 67 men and 106 women (mean age +/- SD 53.3 +/- 11.9 years) without diagnosed diabetes were recruited from the 2004-2005 Australian Diabetes, Obesity, and Lifestyle (AusDiab) study. Physical activity was measured by Actigraph accelerometers worn during waking hours for 7 consecutive days and summarized as sedentary time (accelerometer counts/min <100; average hours/day), light-intensity (counts/min 100-1951), and moderate- to vigorous-intensity (counts/min > or =1,952). An oral glucose tolerance test was used to ascertain 2-h plasma glucose and fasting plasma glucose.RESULTS: After adjustment for confounders (including waist circumference), sedentary time was positively associated with 2-h plasma glucose (b = 0.29, 95% CI 0.11-0.48, P = 0.002); light-intensity activity time (b = -0.25, -0.45 to -0.06, P = 0.012) and moderate- to vigorous-intensity activity time (b = -1.07, -1.77 to -0.37, P = 0.003) were negatively associated. Light-intensity activity remained significantly associated with 2-h plasma glucose following further adjustment for moderate- to vigorous-intensity activity (b = -0.22, -0.42 to -0.03, P = 0.023). Associations of all activity measures with fasting plasma glucose were nonsignificant (P > 0.05).CONCLUSIONS: These data provide the first objective evidence that light-intensity physical activity is beneficially associated with blood glucose and that sedentary time is unfavorably associated with blood glucose. These objective data support previous findings from studies using self-report measures, and suggest that substituting light-intensity activity for television viewing or other sedentary time may be a practical and achievable preventive strategy to reduce the risk of type 2 diabetes and cardiovascular disease.
Healy GN, Dunstan DW, Salmon J, Cerin E, Shaw JE, Zimmet PZ, Owen N. Breaks in sedentary time: beneficial associations with metabolic risk. Diabetes Care. 2008 Apr;31(4):661-6. Epub 2008 Feb 5.

OBJECTIVE: Total sedentary (absence of whole-body movement) time is associated with obesity, abnormal glucose metabolism, and the metabolic syndrome. In addition to the effects of total sedentary time, the manner in which it is accumulated may also be important. We examined the association of breaks in objectively measured sedentary time with biological markers of metabolic risk.RESEARCH DESIGN AND METHODS: Participants (n = 168, mean age 53.4 years) for this cross-sectional study were recruited from the 2004-2005 Australian Diabetes, Obesity and Lifestyle study. Sedentary time was measured by an accelerometer (counts/minute(-1) < 100) worn during waking hours for seven consecutive days. Each interruption in sedentary time (counts/min > or = 100) was considered a break. Fasting plasma glucose, 2-h plasma glucose, serum triglycerides, HDL cholesterol, weight, height, waist circumference, and resting blood pressure were measured. MatLab was used to derive the breaks variable; SPSS was used for the statistical analysis.RESULTS: Independent of total sedentary time and moderate-to-vigorous intensity activity time, increased breaks in sedentary time were beneficially associated with waist circumference (standardized beta = -0.16, 95% CI -0.31 to -0.02, P = 0.026), BMI (beta = -0.19, -0.35 to -0.02, P = 0.026), triglycerides (beta = -0.18, -0.34 to -0.02, P = 0.029), and 2-h plasma glucose (beta = -0.18, -0.34 to -0.02, P = 0.025).CONCLUSIONS: This study provides evidence of the importance of avoiding prolonged uninterrupted periods of sedentary (primarily sitting) time. These findings suggest new public health recommendations regarding breaking up sedentary time that are complementary to those for physical activity.
Healy GN, Dunstan DW, Salmon J, Shaw JE, Zimmet PZ, Owen N. Television time and continuous metabolic risk in physically active adults. Med Sci Sports Exerc. 2008 Apr;40(4):639-45.

PURPOSE: Among Australian adults who met the public health guideline for the minimum health-enhancing levels of physical activity, we examined the dose-response associations of television-viewing time with continuous metabolic risk variables.METHODS: Data were analyzed on 2031 men and 2033 women aged > or = 25 yr from the 1999-2000 Australian Diabetes, Obesity and Lifestyle study without clinically diagnosed diabetes or heart disease, who reported at least 2.5 h.wk of moderate- to vigorous-intensity physical activity. Waist circumference, resting blood pressure, and fasting and 2-h plasma glucose, triglycerides, and high-density-lipoprotein cholesterol (HDL-C) were measured. The cross-sectional associations of these metabolic variables with quartiles and hours per day of self-reported television-viewing time were examined separately for men and for women. Analyses were adjusted for age, education, income, smoking, diet quality, alcohol intake, parental history of diabetes, and total physical activity time, as well as menopausal status and current use of postmenopausal hormones for women.RESULTS: Significant, detrimental dose-response associations of television-viewing time were observed with waist circumference, systolic blood pressure, and 2-h plasma glucose in men and women, and with fasting plasma glucose, triglycerides, and HDL-C in women. The associations were stronger in women than in men, with significant gender interactions observed for triglycerides and HDL-C. Though waist circumference attenuated the associations, they remained statistically significant for 2-h plasma glucose in men and women, and for triglycerides and HDL-C in women.CONCLUSIONS: In a population of healthy Australian adults who met the public health guideline for physical activity, television-viewing time was positively associated with a number of metabolic risk variables. These findings support the case for a concurrent sedentary behavior and health guideline for adults, which is in addition to the public health guideline on physical activity.
Healy GN, Lawler SP, Thorp A, Neuhaus M, Robson EL, Owen N, Dunstan DW. Reducing prolonged sitting in the workplace. An evidence review: Full Report. Healy GN, Lawler SP, Thorp A, Neuhaus M, Robson EL, Owen N, Dunstan DW. Reducing prolonged sitting in the workplace (An evidence review: full report). Melbourne, Australia: Victorian Health Promotion Foundation; 2012.

Available at:
Healy GN, Matthews CE, Dunstan DW, Winkler EA, Owen N. Sedentary time and cardio-metabolic biomarkers in US adults: NHANES 2003-06. Eur Heart J. 2011 Mar;32(5):590-7. Epub 2011 Jan 11.

AIMS: Prolonged sedentary time is ubiquitous in developed economies and is associated with an adverse cardio-metabolic risk profile and premature mortality. This study examined the associations of objectively assessed sedentary time and breaks (interruptions) in sedentary time with continuous cardio-metabolic and inflammatory risk biomarkers, and whether these associations varied by sex, age, and/or race/ethnicity.METHODS AND RESULTS: Cross-sectional analyses with 4757 participants (? 20 years) from the 2003/04 and 2005/06 US National Health and Nutrition Examination Survey (NHANES). An Actigraph accelerometer was used to derive sedentary time [< 100 counts per minute (cpm)] and breaks in sedentary time. Independent of potential confounders, including moderate-to-vigorous exercise, detrimental linear associations (P for trends < 0.05) of sedentary time with waist circumference, HDL-cholesterol, C-reactive protein, triglycerides, insulin, HOMA-%B, and HOMA-%S were observed. Independent of potential confounders and sedentary time, breaks were beneficially associated with waist circumference and C-reactive protein (P for trends <0.05). There was limited evidence of meaningful differences in associations with biomarkers by age, sex, or race/ethnicity. Notable exceptions were sex-differences in the associations of sedentary time and breaks with HDL-cholesterol, and race/ethnicity differences in the association of sedentary time with waist circumference with associations detrimental in non-Hispanic whites, null in Mexican Americans, and beneficial in non-Hispanic blacks.CONCLUSION: These are the first population-representative findings on the deleterious associations of prolonged sedentary time with cardio-metabolic and inflammatory biomarkers. The findings suggest that clinical communications and preventive health messages on reducing and breaking up sedentary time may be beneficial for cardiovascular disease risk.
Healy GN, Wijndaele K, Dunstan DW, Shaw JE, Salmon J, Zimmet PZ, Owen N. Objectively measured sedentary time, physical activity, and metabolic risk: the Australian Diabetes, Obesity and Lifestyle Study (AusDiab). Diabetes Care. 2008 Feb;31(2):369-71. Epub 2007 Nov 13.

OBJECTIVE: We examined the associations of objectively measured sedentary time and physical activity with continuous indexes of metabolic risk in Australian adults without known diabetes.RESEARCH DESIGN AND METHODS: An accelerometer was used to derive the percentage of monitoring time spent sedentary and in light-intensity and moderate-to-vigorous-intensity activity, as well as mean activity intensity, in 169 Australian Diabetes, Obesity and Lifestyle Study (AusDiab) participants (mean age 53.4 years). Associations with waist circumference, triglycerides, HDL cholesterol, resting blood pressure, fasting plasma glucose, and a clustered metabolic risk score were examined.RESULTS: Independent of time spent in moderate-to-vigorous-intensity activity, there were significant associations of sedentary time, light-intensity time, and mean activity intensity with waist circumference and clustered metabolic risk. Independent of waist circumference, moderate-to-vigorous-intensity activity time was significantly beneficially associated with triglycerides.CONCLUSIONS: These findings highlight the importance of decreasing sedentary time, as well as increasing time spent in physical activity, for metabolic health.
Júdice PB, Silva AM, Santos DA, Baptista F, Sardinha LB. Associations of breaks in sedentary time with abdominal obesity in Portuguese older adults. Age (Dordr). 2015;37(2):23.

In older adults, sedentary time is positively associated with obesity. The manner in which it is accumulated, i.e., the number of breaks in sedentary time, might be also important. We examined the cross-sectional associations of breaks in sedentary time with abdominal obesity in 301 older adults (111 men and 190 women) aged 75.0?±?6.8 years. Sedentary time (counts min(-1)?102 cm; women >88 cm). Using binary logistic regression analyses, the odds for abdominal obesity decreased 7 % for each additional hourly break in sedentary time in women (OR?=?0.93, 95 % CI: 0.87-1.00), but not men, independently of total sedentary time and moderate-to-vigorous physical activity. The odds for abdominal obesity were 3.21 times higher (p?=?0.039) for women in quartile 1 (<225 breaks day(-1)) of daily breaks in sedentary time compared to those in quartile 4 (>353 breaks day(-1)) of daily breaks in sedentary time.These findings indicate that older women who interrupt their sedentary time more frequently are less likely to present abdominal obesity. Public health recommendations regarding breaking-up sedentary time complementary to those for physical activity are likely to be relevant.
Júdice PB1, Hamilton MT2, Sardinha LB3, Silva AM4. Randomized controlled pilot of an intervention to reduce and break-up overweight/obese adults' overall sitting-time. Trials. 2015 Nov 2;16:490. doi: 10.1186/s13063-015-1015-4.

BACKGROUND: Too much prolonged sitting is a prevalent health risk among adults. Interventions have focused mainly on the workplace, with limited attention to non-work settings. The effectiveness of a short-term intervention to reduce and break-up sitting-time in overweight/obese adults was examined. This pilot study sought to determine the feasibility of interrupting sitting to stand/ambulate objectively with ActivPAL devices which provide a valid measurement of sit/stand transitions.METHODS: This is a cross-over randomized controlled pilot that included 10 participants (aged 37-65 years) and although a small and short-term intervention (1-week intervention; no washout) further informs on the feasibility of interventions on a larger scale. At the workplace, screen-delivered hourly alerts prompted participants to break-up sitting-time through adopting walking behaviors (approximately 30-60 minutes day(-1)). During transportation/home/leisure-time individual goals for steps day(-1) were set and sitting-reduction strategies (including behavioral self-monitoring) were delivered through daily text messages. Change in inclinometer-derived sitting-time is the main outcome. Standing, stepping, number of sit/stand transitions and participant satisfaction were also examined.RESULTS: For the intervention compared to the control-week (mean difference (95 % confidence interval); p value), participants had less sitting-time (1.85 hours (0.96-2.75); p?=?0.001), more standing (0.77 hours (0.06-1.48); p?=?0.036), and more stepping (1.09 hours (0.79- 1.38); p?
Júdice PB1, Hamilton MT2, Sardinha LB3, Zderic TW4, Silva AM5. What is the metabolic and energy cost of sitting, standing and sit/stand transitions? Eur J Appl Physiol. 2015 Oct 14. [Epub ahead of print]

PURPOSE: Modern lifestyles require people to spend prolonged periods of sitting, and public health messages recommend replacing sitting with as much standing as is feasible. The metabolic/energy cost (MEC) of sitting and standing is poorly understood, and MEC associated with a transition from sitting to standing has not been reported. Thus, we carefully quantified the MEC for sitting, standing and sit/stand transitions, adjusting for age and fat-free mass (FFM) in a sample of adults with no known disease.METHODS: Participants (N = 50; 25 women), 20-64 years, randomly performed three conditions for 10 min each (sitting, standing, 1 sit/stand transition min-1 and then sitting back down). MEC was measured by indirect calorimetry and FFM by dual-energy X-ray absorptiometry.RESULTS: V?O2 (ml kg-1 min-1) for sitting (2.93 ± 0.61; 2.87 ± 0.37 in men and women respectively), standing (3.16 ± 0.63; 3.03 ± 0.40), and steady-state cost of repeated sit/stand transitions (1 min-1) (3.86 ± 0.75; 3.79 ± 0.57) were significantly different regardless of sex and weight (p < 0.001). EE (kcal min-1) also differed from sitting (1.14 ± 0.18; 0.88 ± 0.11), to standing (1.23 ± 0.19; 0.92 ± 0.13), and sit/stand transitions (1 min-1) (1.49 ± 0.25; 1.16 ± 0.16). Heart-rate increased from sitting to standing (~13 bpm; p < 0.001). Neither sex nor FFM influenced the results (p ? 0.05).CONCLUSIONS: This study found in a sample of adults with no known disease that continuous standing raised MEC 0.07 kcal min-1 above normal sitting. The transition from sitting to standing (and return to sitting) had a metabolic cost of 0.32 kcal min-1 above sitting. Therefore, public health messages recommending to interrupt sitting frequently should be informed of the modest energetic costs regardless of sex and body composition.KEYWORDS: Body composition; Breaks; Expenditure; Heart rate; Sedentary behavior
Júdice PB1, Santos DA2, Hamilton MT3, Sardinha LB4, Silva AM5. Validity of GT3X and Actiheart to estimate sedentary time and breaks using ActivPAL as the reference in free-living conditions. Gait Posture. 2015 May;41(4):917-22. doi: 10.1016/j.gaitpost.2015.03.326. Epub 2015 Mar 30.

Sedentary time, specifically sitting/reclining, is a risk factor for many non-communicable diseases and premature mortality. Inclinometers have been used as a valid measurement of sedentary time and its patterns; however, there is a lack of information regarding the validity of alternative accelerometry and heart rate methods. The validity of GT3X and Actiheart in estimating changes in daily sedentary time and breaks, during free-living settings, using ActivPAL as the reference was examined. A crossover randomized control trial of an intervention that aimed to reduce ?3 h/day of sitting time included 10 overweight/obese adults (37-65 years). Participants had a total of 74 valid days for the three devices (29 controls; 45 interventions). For ActivPAL, sedentary time was measured directly based upon posture (sitting/reclining); Actiheart, the presumed MET cutpoint for sedentary time (<1.5 METs) based on accelerometry+heart rate; GT3X, the traditional <100countsmin(-1). A break in sedentary time was defined as when the participants were above the aforementioned cutoffs. GT3X overestimated and Actiheart underestimated sedentary time (bias=135min; bias=-156min, respectively) and both methods overestimated breaks in sedentary time (bias=78; bias=235 breaks, respectively). The GT3X method was in better agreement with the ActivPAL sedentary time (r2=0.70; concordance correlation coefficient (CCC)=0.56) than the Actiheart (r2=0.24; CCC=0.31). The present results highlight the magnitude of potential errors in estimating sedentary time and breaks from common alternative methods other than ActivPAL. Because misclassification errors from the commonly used surrogates are potentially large, this raises concern that alternative methods used in many epidemiological observations may have underestimated the true effects caused by too much sitting (ClinicalTrials.govID:NCT02007681).Copyright © 2015 Elsevier B.V. All rights reserved.KEYWORDS: Inclinometer; Intervention; Motion sensor; Objective methods; Sedentary patterns
Júdice PB1, Silva AM, Magalhães JP, Matias CN, Sardinha LB. Sedentary behaviour and adiposity in elite athletes. J Sports Sci. 2014;32(19):1760-7. doi: 10.1080/02640414.2014.926382. Epub 2014 Jun 10.

Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a health risk. Even in athletes an increased adiposity affects health and performance. Sedentary behaviour has been associated with higher levels of adiposity, independent of moderate-to-vigorous physical activity. However, it is unclear whether this independent relationship still exists in highly trained athletes. The aim of this study was to examine the association of sedentary behaviour with body fatness in elite athletes. Cross-sectional data from 82 male athletes (mean age 22 years) were used. Total and regional body composition was measured by dual energy X-ray absorptiometry. Self-reported time spent in sedentary behaviour and weekly training time was assessed in all participants at one time point and multiple regression analyses were used. Sedentary behaviour predicted total fat mass (? = 0.77; 95% CI: 0.36-1.19, P < 0.001) and trunk fat mass (? = 0.25; 95% CI: 0.07-0.43, P = 0.007), independent of age, weekly training time, and residual mass (calculated as weight-dependent variable) but not abdominal fat. Also, no associations of sedentary behaviour with fat-free mass, appendicular lean soft tissue, and body mass index were found. These findings indicate that athletes with higher amounts of sedentary behaviour presented higher levels of total and trunk fatness, regardless of age, weekly training time, and residual mass. Therefore, even high moderate-to-vigorous physical activity levels do not mitigate the associations between sedentary behaviour and body fatness in highly trained athletes.KEYWORDS: athletes; body composition; fat mass; physical activity; trunk fat mass
Júdice PB1, Silva AM, Sardinha LB. Sedentary Bout Durations Are Associated with Abdominal Obesity in Older Adults. J Nutr Health Aging. 2015 Oct;19(8):798-804. doi: 10.1007/s12603-015-0501-4.

OBJECTIVES: In older adults, sedentary behavior has been positively associated with obesity and impaired metabolic health, additional to low moderate-to-vigorous physical activity (MVPA). Further to the total time spent in sedentary behavior, the manner in which it is accumulated – number of continuous sedentary bouts of different extends – may also be relevant. The association for objectively measured uninterrupted sedentary bouts and respective patterns with abdominal obesity in older adults was examined.DESIGN: Cross-sectional.SETTING: Community-based older people were recruited in each region of Portugal. Data collection was performed between September, 2007 and May, 2009.PARTICIPANTS: 351 older adults (230 women) mean age of 75-years.MEASUREMENTS: Sedentary time was measured by an accelerometer (counts/minute <100), worn during waking hours for four consecutive days. Continuous sedentary bouts of 560 length were treated (counts/minute <100). Abdominal obesity was defined by waist circumference (men>102 cm; women>88 cm).RESULTS: There were positive and escalating linear associations for the continuum of sedentary bouts’ lengths with waist circumference. Logistic regression showed that for each additional sedentary bout of 10< min<20 the odds of being abdominally obese increased by 6.8% (OR=1.07, 95% CI: 1.02 – 1.13) up to 48% (OR=1.48, 95% CI: 1.07 – 2.03) for each 1-hour sedentary bout increment, after controlling for age, gender, total sedentary time, MVPA time, total wear time, movement counts within the sedentary bouts, socio-demographic and other behavioral attributes, and medical history.CONCLUSION: These findings indicate positive graded associations for continuous sedentary bouts with abdominal obesity. Public health recommendations regarding breaking up sedentary time more often, potentially avoiding very prolonged bouts of sedentary time, are expected to be relevant for older adults.
Katzmarzyk PT, Church TS, Craig CL, Bouchard C. Sitting time and mortality from all causes, cardiovascular disease, and cancer. Med Sci Sports Exerc. 2009 May;41(5):998-1005.

PURPOSE: Although moderate-to-vigorous physical activity is related to premature mortality, the relationship between sedentary behaviors and mortality has not been fully explored and may represent a different paradigm than that associated with lack of exercise. We prospectively examined sitting time and mortality in a representative sample of 17,013 Canadians 18-90 yr of age.METHODS: Evaluation of daily sitting time (almost none of the time, one fourth of the time, half of the time, three fourths of the time, almost all of the time), leisure time physical activity, smoking status, and alcohol consumption was conducted at baseline. Participants were followed prospectively for an average of 12.0 yr for the ascertainment of mortality status.RESULTS: There were 1832 deaths (759 of cardiovascular disease (CVD) and 547 of cancer) during 204,732 person-yr of follow-up. After adjustment for potential confounders, there was a progressively higher risk of mortality across higher levels of sitting time from all causes (hazard ratios (HR): 1.00, 1.00, 1.11, 1.36, 1.54; P for trend <0.0001) and CVD (HR:1.00, 1.01, 1.22, 1.47, 1.54; P for trend <0.0001) but not cancer. Similar results were obtained when stratified by sex, age, smoking status, and body mass index. Age-adjusted all-cause mortality rates per 10,000 person-yr of follow-up were 87, 86, 105, 130, and 161 (P for trend <0.0001) in physically inactive participants and 75, 69, 76, 98, 105 (P for trend = 0.008) in active participants across sitting time categories.CONCLUSIONS: These data demonstrate a dose-response association between sitting time and mortality from all causes and CVD, independent of leisure time physical activity. In addition to the promotion of moderate-to-vigorous physical activity and a healthy weight, physicians should discourage sitting for extended periods.
Kempen KP, Saris WH, Westerterp KR. Energy balance during an 8-wk energy-restricted diet with and without exercise in obese women. Am J Clin Nutr. 1995 Oct;62(4):722-9.

The effects of severe energy restriction alone (2.0 MJ/d for 4 wk and subsequently 3.5 MJ/d for 4 wk) or energy restriction plus moderate exercise on energy balance were studied in 20 healthy obese women. Subjects aged 25-50 y were matched on the basis of body mass index and percentage body fat and randomly assigned to diet alone (D) or diet and exercise (DE) for 8 wk. DE resulted in a significantly increased loss of fat mass compared with D (7.8 +/- 0.8 compared with 5.5 +/- 0.8 kg; P < 0.05). The average daily metabolic rate measured with doubly labeled water decreased with both treatments, with no differences between the treatments. Energy balance data show that the DE treatment resulted in a significantly greater energy deficit than the D treatment. The relative contribution of fat to energy expenditure during exercise was significantly enhanced by DE treatment whereas it did not change after D. The energy expended on physical activity was not changed at the end of both treatments, with no differences between the two groups. The unchanged energy expended on physical activity indicates that DE might be accompanied by partial compensation of daily physical activities outside the training for the energy expended during the training. The energy deficit due to energy restriction alone was not compensated by a decrease in free-living daily physical activities. Addition of moderate exercise to an energy-restriction program in obese women has advantages with respect to changes in body composition, energy expenditure, and substrate utilization.
Kim J, Tanabe K, Yokoyama N, Zempo H, Kuno S Objectively measured light-intensity lifestyle activity and sedentary time are independently associated with metabolic syndrome: a cross-sectional study of Japanese adults Int J Behav Nutr Phys Act. 2013 Mar 4;10:30. doi: 10.1186/1479-5868-10-30.

BACKGROUND:Reducing sedentary time and increasing lifestyle activities, including light-intensity activity, may be an option to help prevent metabolic syndrome (MetS). The purpose of the present study was to examine whether objectively measured light-intensity lifestyle activity and sedentary time is associated with MetS, independent of moderate-vigorous intensity physical activity (MVPA). METHODS:The participants in this cross-sectional study were 483 middle-aged Japanese adults, aged 30-64 years. The participants were divided into those with or without MetS according to the Japanese criteria for MetS. A triaxial accelerometer was used to measure light-intensity lifestyle activity [1.6-2.9 metabolic equivalents (METs)] and sedentary time (?1.5 METs). Logistic regression was used to predict MetS from the levels of light-intensity lifestyle activity and sedentary time with age, sex, smoking, calorie intake, accelerometer wear time, and MVPA as covariates. RESULTS:The odds ratios (OR) for MetS in the highest and middle tertiles of light-intensity lifestyle activity were 0.44 [95% confidence interval (CI): 0.24 to 0.81] and 0.51 (95% CI: 0.29 to 0.89) relative to the lowest tertile, after adjustment for age, sex, smoking, calorie intake, accelerometer wear time and MVPA (Ptrend?=?0.012). Sedentary time was also associated with the risk of MetS (Ptrend?=?0.018). Among participants in the highest tertile of sedentary time, the risk of MetS was 2.27-times greater than that in the lowest tertile (95% CI: 1.25 to 4.11). The risk of MetS was not significantly increased in subjects in the middle tertile of sedentary time. CONCLUSIONS:We found that light-intensity lifestyle activity and sedentary time were significantly associated with the risk of MetS, independent of MVPA. The results of our study suggest that public health messages and guidelines should be refined to include increases in light-intensity lifestyle activity and/or decreases in sedentary time, alongside promoting MVPA, to prevent MetS.
Koepp GA, Manohar CU, McCrady-Spitzer SK, Ben-Ner A, Flint-Paulson D, Runge CF, Levine JA. Treadmill desks: A one-year prospective trial. Obesity (Silver Spring). 2012 Nov 6. doi: 10.1002/oby.20121. [Epub ahead of print]

Sedentariness is associated with weight gain and obesity. A Treadmill Desk is the combination of a standing desk and a treadmill that allow employees to work while walking at low speed. The hypothesis was that a one-year intervention with Treadmill Desks is associated with an increase in employee Daily Physical Activity (summation of all activity per minute) and a decrease in Daily Sedentary Time (zero activity). Employees (n=36; 25 women, 11 men) with sedentary jobs (87 + 27 kg, BMI 29 + 7 kg/m(2) ; n=10 Lean BMI<25 kg/m(2) , n=15 Overweight 2530 kg/m(2) ) volunteered to have their traditional desk replaced with a Treadmill Desk to promote physical activity for one year. Daily Physical Activity (using accelerometers), work performance, body composition, and blood variables were measured at Baseline and 6 and 12 months after the Treadmill Desk intervention. Subjects who used the Treadmill Desk increased Daily Physical Activity from Baseline, 3353 + 1802 Activity Units (AU)/day to, at 6 months, 4460 + 2376 AU/day (P<0.001) and at 12 months, 4205 + 2238 AU/day (P<0.001). Access to the Treadmill Desks was associated with significant decreases in Daily Sedentary Time (zero activity) from, at Baseline 1020 + 75 min/day to, at 6 months 929 + 84 min/day (P<0.001) and at 12 months, 978 + 95 min/day (P<0.001). For the whole group, weight loss averaged 1.4 + 3.3 kg (P<0.05). Weight loss for obese subjects was, 2.3 + 3.5 kg (P<0.03). Access to the Treadmill Desks was associated with increased Daily Physical Activity compared to traditional chair-based desks; their deployment was not associated with altered performance. For the 36 participants, fat mass did not change significantly, however, those who lost weight (n=22) lost 3.4 + 5.4 kg (P<0.001) of fat mass. Weight loss was greatest in people with obesity.Copyright © 2012 The Obesity Society.
Koster A, Caserotti P, Patel KV, Matthews CE, Berrigan D, Van Domelen DR, Brychta RJ, Chen KY, Harris TB. Association of sedentary time with mortality independent of moderate to vigorous physical activity. PLoS One. 2012;7(6):e37696. Epub 2012 Jun 13.

BACKGROUND: Sedentary behavior has emerged as a novel health risk factor independent of moderate to vigorous physical activity (MVPA). Previous studies have shown self-reported sedentary time to be associated with mortality; however, no studies have investigated the effect of objectively measured sedentary time on mortality independent of MVPA. The objective our study was to examine the association between objectively measured sedentary time and all-cause mortality.METHODS: 7-day accelerometry data of 1906 participants aged 50 and over from the U.S. nationally representative National Health and Nutrition Examination Survey (NHANES) 2003-2004 were analyzed. All-cause mortality was assessed from the date of examination through December 31, 2006.RESULTS: Over an average follow-up of 2.8 years, there were 145 deaths reported. In a model adjusted for sociodemographic factors, lifestyle factors, multiple morbidities, mobility limitation, and MVPA, participants in third quartile (hazard ratio (HR):4.05; 95%CI:1.55-10.60) and fourth quartile (HR:5.94; 95%CI: 2.49-14.15) of having higher percent sedentary time had a significantly increased risk of death compared to those in the lowest quartile.CONCLUSIONS: Our study suggests that sedentary behavior is a risk factor for mortality independent of MVPA. Further investigation, including studies with longer follow-up, is needed to address the health consequences of sedentary behavior.
Kwon S, Burns TL, Levy SM, Janz KF. Breaks in Sedentary Time during Childhood and Adolescence: Iowa Bone Development Study. Med Sci Sports Exerc. 2012 Jun;44(6):1075-80.

PURPOSE: The frequency of interruptions in sedentary time (sedentary breaks) is an aspect of sedentary behaviors that may be associated with metabolic health outcomes. The aim of this study was to describe the change in the frequency of sedentary breaks during a 10-yr period from ages 5 to 15 yr.METHODS: The longitudinal Iowa Bone Development Study has collected accelerometry data at approximately 5, 8, 11, 13, and 15 yr. Data from participants who wore an accelerometer at least 10 h·d and 3 d per data collection episode were used (423 children at age 5 yr, 550 children at age 8 yr, 520 children at age 11 yr, 454 children at age 13 yr, and 344 children at age 15 yr). The frequency of sedentary breaks was determined based on accelerometry data and compared by weekday/weekend, period during the day, gender, and data collection episode.RESULTS: The frequency of sedentary breaks decreased by >200 times per day during a 10-yr period from ages 5 to 15 yr. Linear regression models estimated a 1.84-times-per-hour decrease per year for boys and a 2.04-times-per-hour decrease per year for girls (P values < 0.0001). Both boys and girls showed significantly fewer breaks on weekdays from morning to 3:00 p.m. than on weekends from morning to 3:00 p.m. (P values < 0.0001). The frequency of sedentary breaks was slightly higher among boys than among girls (gender difference ?2 times per hour; P values < 0.01 at ages 11, 13, and 15 yr).CONCLUSIONS: Breaks in sedentary time notably decrease during childhood and adolescence. During school hours, boys and girls have fewer breaks in sedentary time than during any other period of weekday or weekend day.
Lakerveld J, Bot SD, van der Ploeg HP, Nijpels G. The effects of a lifestyle intervention on leisure-time sedentary behaviors in adults at risk: The Hoorn Prevention Study, a randomized controlled trial. Prev Med. 2013 Jun 15. pii: S0091-7435(13)00203-X. doi: 10.1016/j.ypmed.2013.06.011. [Epub ahead of print]

OBJECTIVE: This study set out to assess the short and long-term effects of a primary care based lifestyle intervention on different domains of leisure-time sedentary behaviors in Dutch adults at risk of type 2 diabetes and cardiovascular diseases.METHOD: Between 2007 and 2009, adults (n=622) at risk were randomly assigned to a counseling intervention aimed at adopting healthy lifestyle behaviors, or a control group that only received health brochures. Follow-up measures were done after 6, 12 and 24 months. Linear regression analysis was used to examine between-group differences in self report minutes per day sedentary behaviors, adjusted for baseline values. Stratified analyses were performed for sex and educational attainment.RESULTS: Seventy-nine percent (n=490) of participants completed the last follow-up. Mean baseline sedentary behaviors were 254.6 minutes per day (SD 136.2). Intention-to-treat analyses showed no significant differences in overall or domain specific sedentary behaviors between the two groups at follow-up. Stratified analyses for educational attainment revealed a small and temporary between-group difference in favor of the intervention group, in those who finished secondary school.CONCLUSIONS: A primary care based general lifestyle intervention was not more effective in reducing leisure-time sedentary behaviors than providing brochures, in adults at risk for chronic diseases.Copyright © 2013. Published by Elsevier Inc.
Lakerveld J, Dunstan D, Bot S, Salmon J, Dekker J, Nijpels G, Owen N. Abdominal obesity, TV-viewing time and prospective declines in physical activity. Prev Med. 2011 Oct;53(4-5):299-302. Epub 2011 Jul 23.

OBJECTIVE: To examine the prospective associations of baseline abdominal obesity and TV-viewing time with five-year reductions in leisure-time physical activity level.METHODS: We used data from the Australian Diabetes, Obesity and Lifestyle Study (AusDiab), a nationally representative population-based cohort study with measures collected in 1999-2000 and 2004-2005. Abdominal obesity was determined by waist circumference and TV-viewing time and physical activity level were assessed using established interviewer-administered questionnaires.RESULTS: Among 2,191 men and 2,650 women aged ? 25years, odds ratios (ORs) of 5-year reductions from sufficient to insufficient or no physical activity, and from insufficient to no physical activity were estimated with logistic regression. We adjusted for sociodemographic characteristics. The odds of reducing physical levels from baseline to the follow-up survey for obese men (34.2%) and women (38.1%), respectively were 1.40 (1.10-1.79) and 1.44 (1.16-1.80), compared to those with a normal waist circumference. Women, but not men, with higher levels of TV-viewing time had higher odds of reducing physical activity levels (8.6%; OR 1.46; 1.01-2.11), independent of abdominal obesity.CONCLUSIONS: These findings suggest that abdominal obesity is associated with prospective reductions in physical activity level, and that high levels of TV-viewing time might have an additional adverse influence for women.Copyright © 2011 Elsevier Inc. All rights reserved.
Lara A, Yancey AK, Tapia-Conye R, Flores Y, Kuri-Morales P, Mistry R, Subirats E, McCarthy WJ. Pausa para tu Salud: reduction of weight and waistlines by integrating exercise breaks into workplace organizational routine. Prev Chronic Dis. 2008 Jan;5(1):A12. Epub 2007 Dec 15.

INTRODUCTION: Proactive worksite strategies that change the physical or sociocultural environment(s) to incorporate obligatory physical activity may be necessary to engage sedentary people. This study describes implementation and evaluation of an intervention, Pausa para tu Salud (Pause for Your Health), that integrated a brief period of group exercise into the workday.METHODS: An uncontrolled pretest-post-test study design tested the effects of integrating daily 10-minute exercise breaks during paid work time during January 2003 through January 2004. A total of 335 Mexican Ministry of Health office workers provided baseline data as a part of routine annual clinical screening examinations.RESULTS: Baseline mean body mass index and waist circumferences were 27.8 kg/m(2) and 87.6 cm for women and 26.6 kg/m(2) and 89.7 cm for men. Complete data were available for 271 (80.9%) employees at 1-year follow-up. Two-tailed, paired t-test comparisons were used. Body mass index decreased by 0.32 kg/m(2) (P = .05), and waist circumference by 1.6 cm (P = .0009) overall. The body mass index decrease, however, was significant only for men (-0.43 kg/m(2), P = .03). Multivariate analyses revealed a significant decrease in diastolic blood pressure among women (z = -2.04, P = .042).CONCLUSION: The intervention was associated with significant improvements in both measures of body composition. Substantive health and organizational benefits may result from integrating brief periods of physical activity into the workday if these findings are replicated in randomized controlled trials in other worksites.
Lee J1, Chang RW, Ehrlich-Jones L, Kwoh CK, Nevitt M, Semanik PA, Sharma L, Sohn MW, Song J, Dunlop DD. Sedentary behavior and physical function: objective evidence from the Osteoarthritis Initiative. Arthritis Care Res (Hoboken). 2015 Mar;67(3):366-73. doi: 10.1002/acr.22432.

OBJECTIVE: Investigate the relationship between sedentary behavior and physical function in adults with knee osteoarthritis (OA), controlling for moderate-vigorous physical activity (MVPA) levels.METHODS: Sedentary behavior was objectively measured by accelerometer on 1,168 participants ages 49-83 years in the Osteoarthritis Initiative with radiographic knee OA at the 48-month clinic visit. Physical function was assessed using 20-meter walk and chair stand testing. Sedentary behavior was identified by accelerometer activity counts/minute <100. The cross-sectional association between sedentary quartiles and physical function was examined by multiple linear regression, adjusting for demographic factors (age, sex, race/ethnicity, education level), health factors (comorbidity, body mass index, knee pain, knee OA severity, presence of knee symptoms), and average daily MVPA minutes.RESULTS: Adults with knee OA spent two-thirds of their daily time in sedentary behavior. The average gait speed among the most sedentary quartile was 3.88 feet/second, which was significantly slower than the speed of the less sedentary groups (4.23, 4.33, and 4.33 feet/second, respectively). The average chair stand rate among the most sedentary group was significantly lower (25.9 stands/minute) than the rates of the less sedentary behavior groups (28.9, 29.1, and 31.1 stands/minute, respectively). These trends remained significant in multivariable analyses adjusted for demographic factors, health factors, and average daily MVPA minutes.CONCLUSION: Being less sedentary was related to better physical function in adults with knee OA independent of MVPA time. These findings support guidelines to encourage adults with knee OA to decrease time spent in sedentary behavior in order to improve physical function.Copyright © 2015 by the American College of Rheumatology.
Leelarungrayub D, Khansuwan R, Pothongsunun P, Klaphajone J. N-Acetylcysteine Supplementation Controls Total Antioxidant Capacity, Creatine Kinase, Lactate, and Tumor Necrotic Factor-Alpha against Oxidative Stress Induced by Graded Exercise in Sedentary Men. Oxid Med Cell Longev. 2011;2011:329643. Epub 2011 Aug 23.

Aim of this study was to evaluate the effects of short-term (7 days) N-acetylcysteine (NAC) at 1,200?mg daily supplementation on muscle fatigue, maximal oxygen uptake (VO(2max?)), total antioxidant capacity (TAC), lactate, creatine kinase (CK), and tumor necrotic factor-alpha (TNF-?). Twenty-nine sedentary men (13 controls; 16 in the supplement group) from a randomized control were included. At before and after supplementation, fatigue index (FI) was evaluated in the quadriceps muscle, and performed a graded exercise treadmill test to induce oxidative stress, and as a measure of VO(2max?). Blood samples were taken before exercise and 20 minutes after it at before and after supplementation, to determine TAC, CK, lactate, and TNF-? levels. Results showed that FI and VO(2max?) increased significantly in the supplement group. After exercise decreased the levels of TAC and increased lactate, CK, and TNF-? of both groups at before supplementation. After supplementation, lactate, CK, and TNF-? levels significantly increased and TAC decreased after exercise in the control group. Whereas the TAC and lactate levels did not change significantly, but CK and TNF-? increased significantly in the supplement group. Therefore, this results showed that NAC improved the muscle fatigue, VO(2max?), maintained TAC, controlled lactate production, but had no influence on CK and TNF-?.
Levine JA, Eberhardt NL, Jensen MD. Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science. 1999 Jan 8;283(5399):212-4.

Humans show considerable interindividual variation in susceptibility to weight gain in response to overeating. The physiological basis of this variation was investigated by measuring changes in energy storage and expenditure in 16 nonobese volunteers who were fed 1000 kilocalories per day in excess of weight-maintenance requirements for 8 weeks. Two-thirds of the increases in total daily energy expenditure was due to increased nonexercise activity thermogenesis (NEAT), which is associated with fidgeting, maintenance of posture, and other physical activities of daily life. Changes in NEAT accounted for the 10-fold differences in fat storage that occurred and directly predicted resistance to fat gain with overfeeding (correlation coefficient = 0.77, probability < 0.001). These results suggest that as humans overeat, activation of NEAT dissipates excess energy to preserve leanness and that failure to activate NEAT may result in ready fat gain.Comment inScience. 1999 May 14;284(5417):1125-6. Science. 1999 Jan 8;283(5399):184-5.
Levine JA, Lanningham-Foster LM, McCrady SK, Krizan AC, Olson LR, Kane PH, Jensen MD, Clark MM. Interindividual variation in posture allocation: possible role in human obesity. Science. 2005 Jan 28;307(5709):584-6.

Obesity occurs when energy intake exceeds energy expenditure. Humans expend energy through purposeful exercise and through changes in posture and movement that are associated with the routines of daily life [called nonexercise activity thermogenesis (NEAT)]. To examine NEAT’s role in obesity, we recruited 10 lean and 10 mildly obese sedentary volunteers and measured their body postures and movements every half-second for 10 days. Obese individuals were seated, on average, 2 hours longer per day than lean individuals. Posture allocation did not change when the obese individuals lost weight or when lean individuals gained weight, suggesting that it is biologically determined. If obese individuals adopted the NEAT-enhanced behaviors of their lean counterparts, they might expend an additional 350 calories (kcal) per day.Comment inScience. 2005 Jan 28;307(5709):530-1.
Levine JA, Vander Weg MW, Hill JO, Klesges RC. Non-exercise activity thermogenesis: the crouching tiger hidden dragon of societal weight gain. Arterioscler Thromb Vasc Biol. 2006 Apr;26(4):729-36. Epub 2006 Jan 26.

Non-exercise activity thermogenesis (NEAT) is the energy expenditure of all physical activities other than volitional sporting-like exercise. NEAT includes all the activities that render us vibrant, unique, and independent beings such as working, playing, and dancing. Because people of the same weight have markedly variable activity levels, it is not surprising that NEAT varies substantially between people by up to 2000 kcal per day. Evidence suggests that low NEAT may occur in obesity but in a very specific fashion. Obese individuals appear to exhibit an innate tendency to be seated for 2.5 hours per day more than sedentary lean counterparts. If obese individuals were to adopt the lean “NEAT-o-type,” they could potentially expend an additional 350 kcal per day. Obesity was rare a century ago and the human genotype has not changed over that time. Thus, the obesity epidemic may reflect the emergence of a chair-enticing environment to which those with an innate tendency to sit, did so, and became obese. To reverse obesity, we need to develop individual strategies to promote standing and ambulating time by 2.5 hours per day and also re-engineer our work, school, and home environments to render active living the option of choice.
Levine JA. Nonexercise activity thermogenesis--liberating the life-force. J Intern Med. 2007 Sep;262(3):273-87.

Obesity occurs when energy intake exceeds energy expenditure over a protracted period of time. The energy expenditure associated with everyday activity is called NEAT (Nonexercise activity thermogenesis). NEAT varies between two people of similar size by 2000 kcal day(-1) because of people’s different occupations and leisure-time activities. Data support the central hypothesis that NEAT is pivotal in the regulation of human energy expenditure and body weight regulation and that NEAT is important for understanding the cause and effective treatment for obesity.
Lubans DR, Hesketh K, Cliff DP, Barnett LM, Salmon J, Dollman J, Morgan PJ, Hills AP, Hardy LL. A systematic review of the validity and reliability of sedentary behaviour measures used with children and adolescents Obesity Reviews, 2011, 12(10): 759-885.

The aim of this review was to evaluate the reliability and validity of methods used to assess the multiple components of sedentary behaviour (i.e. screen time, sitting, not moving and existing at low energy expenditure) in children and adolescents. Twenty-six studies met our inclusion criteria and were reviewed. Thirteen studies reported the reliability of self- and proxy-report measures of sedentary behaviour and seven of these were found to have acceptable test–retest reliability. Evidence for the criterion validity of self- and proxy-report measures was examined in three studies with mixed results. Seven studies examined the reliability and/or validity of direct observation and the findings were generally positive. Five studies demonstrated the utility of accelerometers to accurately classify sedentary behaviour. Self-report measures provide reliable estimates of screen time, yet their validity remains largely untested. While accelerometers can accurately classify participants\' behaviour as sedentary, they do not provide information about type of sedentary behaviour or context. Studies utilizing measures of sedentary behaviour need to more adequately report on the validity and reliability of the measures used. We recommend the use of objective measures of sedentary behaviour such as accelerometers, in conjunction with subjective measures (e.g. self-report), to assess type and context of behaviour.
Lucas J Carr, Kristen A Walaska, Bess H Marcus Feasibility of a portable pedal exercise machine for reducing sedentary time in the workplace British Journal of Sports Br J Sports Med doi:10.1136/bjsm.2010.079574

Background Sedentary time is independently associated with an increased risk of metabolic disease. Worksite interventions designed to decrease sedentary time may serve to improve employee health. Objective The purpose of this study is to test the feasibility and use of a pedal exercise machine for reducing workplace sedentary time. Methods Eighteen full-time employees (mean age+SD 40.2+10.7 years; 88% female) working in sedentary occupations were recruited for participation. Demographic and anthropometric data were collected at baseline and 4 weeks. Participants were provided access to a pedal exercise machine for 4 weeks at work. Use of the device was measured objectively by exercise tracking software, which monitors pedal activity and provides the user real-time feedback (eg, speed, time, distance, calories). At 4 weeks, participants completed a feasibility questionnaire. Results Participants reported sitting 83% of their working days. Participants used the pedal machines an average of 12.2+6.6 out of a possible 20 working days and pedalled an average of 23.4+20.4 min each day used. Feasibility data indicate that participants found the machines feasible for use at work. Participants also reported sedentary time at work decreased due to the machine. Discussion Findings from this study suggest that this pedal machine may be a feasible tool for reducing sedentary time while at work. These findings hold public health significance due to the growing number of sedentary jobs in the USA and the potential of the device for use in large-scale worksite health programmes.
Lynch BM, Cerin E, Owen N, Hawkes AL, Aitken JF. Television viewing time of colorectal cancer survivors is associated prospectively with quality of life. Cancer Causes Control. 2011 Aug;22(8):1111-20. Epub 2011 Jun 9.

OBJECTIVE: To examine prospective associations of television viewing time with quality of life, following a colorectal cancer diagnosis.METHODS: One thousand, nine hundred and sixty-six colorectal cancer survivors were recruited through the Queensland Cancer Registry. Interviews were conducted at 5, 12, 24, and 36 months post-diagnosis. Generalized linear mixed models estimated the effects of television viewing time on quality of life.RESULTS: Participants who watched ?5 h of television per day had a 16% lower total quality of life score than did participants reporting ?2 h per day. Deleterious associations of television viewing time were found with all quality of life subscales: functional well-being showed the strongest association (23% difference in quality of life scores between highest and lowest television viewing categories), and social well-being the weakest association (6% difference). Participants who increased their television viewing by one category (e.g., ?2 h, increasing to 3-4 h per day) had a proportional decrease of some 6% in their quality of life score (intra-individual effect).CONCLUSIONS: The deleterious associations of television viewing time with quality of life were clinically significant and consistent over time. Decreasing sedentary behavior may be an important behavioral strategy to enhance the quality of life of cancer survivors.
Lynch BM, Courneya KS, Friedenreich CM. A case-control study of lifetime occupational sitting and likelihood of breast cancer. Cancer Causes Control. 2013 Jun;24(6):1257-62. doi: 10.1007/s10552-013-0194-0. Epub 2013 Mar 24.

PURPOSE: Sedentary behavior may be a unique risk factor for some cancers, including breast cancer. The objective of this study was to determine the association between lifetime occupational sitting and likelihood of breast cancer.METHODS: A case-control study of 2,452 women was conducted in Alberta, Canada, between 1995 and 1997. A comprehensive measure of lifetime physical activity assessed frequency and duration of sedentary jobs. Logistic regression estimated the odds of being diagnosed with breast cancer across quartiles of lifetime occupational sitting, by menopausal status and family history of breast cancer, and within body mass index categories and physical activity quartiles.RESULTS: There was no association between occupational sitting and breast cancer among pre-menopausal women and women with a family history of breast cancer. Unexpectedly, higher amounts of occupational sitting were associated with lower odds of breast cancer in post-menopausal women (top versus bottom categories of occupational sitting OR = 0.71, 95 % CI 0.52, 0.97), women without a family history of breast cancer (OR = 0.77, 95 % CI 0.60, 1.00), and women in the third highest quartile of total lifetime physical activity (OR = 0.57, 95 % CI 0.33, 0.97).CONCLUSION: Occupational sitting levels were lower than would be expected in a contemporary study. Exposures may have been insufficient to make a determinable contribution to breast cancer risk.
Lynch BM, Dunstan DW, Healy GN, Winkler E, Eakin E, Owen N. Objectively measured physical activity and sedentary time of breast cancer survivors, and associations with adiposity: findings from NHANES (2003-2006). Cancer Causes Control. 2010 Feb;21(2):283-8. Epub 2009 Nov 1.

OBJECTIVE: Obesity and physical inactivity are poor prognostic indicators for breast cancer. Studies to date have relied on self-report measures of physical activity, which tend mainly to assess moderate-to-vigorous intensity leisure-time physical activity. We report the cross-sectional associations of objectively assessed physical activity and sedentary time with adiposity in a sample of breast cancer survivors from the United States.METHODS: One hundred and eleven women from the National Health and Nutrition Examination Survey (NHANES) 2003-2004 and 2005-2006 reported a history of breast cancer. Participants wore an accelerometer for 7 days, and activity levels were summarized as moderate-to-vigorous intensity (accelerometer counts/min > or =1,952), light intensity (counts/min 100-1,951), and sedentary time (counts/min <100). Anthropometric measures were taken by study staff at examination centers.RESULTS: Participants spent the majority of their day in sedentary time (66%) or in light intensity activities (33%). Log moderate-to-vigorous intensity physical activity was negatively associated with adiposity (waist circumference beta = -9.805 [95% CI: -15.836, -3.775]; BMI beta = -3.576 [95% CI: -6.687, -0.464]). Light intensity physical activity was negatively associated with adiposity; however, the fully adjusted models did not retain statistical significance. Similarly, sedentary time was positively associated with adiposity, but the fully adjusted models were not statistically significant.CONCLUSIONS: This is the first study to describe the objectively assessed physical activity and sedentary time of breast cancer survivors. Increasing moderate-to-vigorous and light intensity physical activity, and decreasing sedentary time, may assist with weight management and improve other metabolic health outcomes for breast cancer survivors.
Lynch BM, Dunstan DW, Vallance JK, Owen N. Don't take cancer sitting down: a new survivorship research agenda. Cancer. 2013 Jun 1;119(11):1928-35. doi: 10.1002/cncr.28028. Epub 2013 Mar 15.

Cancer survival is associated with considerable physical and psychosocial burden. Broadly accessible, nonpharmacologic measures that may extend disease-free survival, limit comorbid disease, and enhance quality of life are required. Sedentary behavior (too much sitting) is now understood to be a health risk that is additional to, and distinct from, the hazards of too little exercise. Of particular note, it is associated with adiposity, insulin resistance, and markers of inflammation. Therefore, it is plausible that sedentary behavior may contribute to adverse cancer outcomes (disease progression, recurrence, or death) and to the development of comorbid chronic disease. Initial studies indicate that cancer survivors spend two-thirds of their waking hours sitting. Among colorectal cancer survivors, sedentary behavior may contribute to all-cause and disease-specific mortality, weight gain, comorbid cardiovascular disease, and diminished quality of life. There is a need for dose-response evidence, and for a broader understanding of the underlying mechanisms by which prolonged sitting time may affect cancer survivors’ health.Copyright © 2013 American Cancer Society.
Lynch BM, Dunstan DW, Winkler E, Healy GN, Eakin E, Owen N. Objectively assessed physical activity, sedentary time and waist circumference among prostate cancer survivors: findings from the National Health and Nutrition Examination Survey (2003-2006). Eur J Cancer Care (Engl). 2011 Jul;20(4):514-9. doi: 10.1111/j.1365-2354.2010.01205.x. Epub 2010 Jun 29.

Physical activity is well-established on the cancer survivorship research agenda, but prostate cancer survivors remain an understudied population. Additionally, the unique relationships between sedentary time and health outcomes have not yet been considered in this group. We examined the associations of accelerometer-assessed physical activity and sedentary time with waist circumference in 103 prostate cancer survivors from the National Health and Nutrition Examination Survey 2003-2004 and 2005-2006. Participants wore an Actigraph accelerometer for 7 days, and activity levels were summarised as moderate-to-vigorous intensity activity (accelerometer counts/minute ? 1952), light-intensity activity (counts/minute 100-1951) and sedentary time (counts/minute < 100). Moderate-to-vigorous intensity physical activity was inversely associated with waist circumference (?=-6.728, 95% CI: -12.267, -1.190, P= 0.020), equating to a top versus bottom quartile difference of 13.7 cm. No discernable relationship existed between light-intensity activity or sedentary time and adiposity. This is the first study to objectively measure the activity levels of prostate cancer survivors. Increasing moderate-to-vigorous activity may assist this population with weight management. More research into the relationships of light-intensity physical activity and sedentary behaviour with health outcomes among prostate cancer survivors is warranted, given the strong relationships seen in the broader population.© 2010 Blackwell Publishing Ltd.
Lynch BM, Friedenreich CM, Kopciuk KA, Hollenbeck AR, Moore SC, Matthews CE. Sedentary behavior and prostate cancer risk in the NIH-AARP Diet and Health Study. Cancer Epidemiol Biomarkers Prev. 2014 May;23(5):882-9. doi: 10.1158/1055-9965.EPI-13-0808. Epub 2014 Feb 13.

Sedentary behavior (sitting time) has been proposed as an independent risk factor for some cancers; however, its role in the development of prostate cancer has not been determined. We examined the prospective associations of self-reported daily sitting time and daily television/video viewing time with the risk of developing or dying from prostate cancer among 170,481 men in the NIH-AARP Diet and Health Study. We estimated HRs and 95% confidence intervals (CI) using Cox proportional hazards regression. Between 1996 and 2006, there were 13,751 incident (including 1,365 advanced) prostate cancer cases identified; prostate cancer mortality (through 2008) was 669. No strong or significant association with prostate cancer risk was seen in fully adjusted models for either daily sitting or television/video time. There were some suggestions of effect modification by body mass index (BMI; interaction for television/video time and BMI, P = 0.02). For total prostate cancer risk, television/video time was associated with a slightly elevated, but nonsignificant, increase amongst obese men (HR = 1.28; 95% CI, 0.98-1.69); a null association was observed amongst overweight men (HR = 1.04; 0.89-1.22); and, for men with a normal BMI, television/video time was associated with a nonsignificant risk decrease (HR = 0.82; 95% CI, 0.66-1.01). Similar patterns were observed for total daily sitting and television/video time in advanced prostate cancer and prostate cancer mortality. Sedentary behavior seems to play a limited role in the development of prostate cancer; however, we cannot rule out potential effect modification by BMI or the impact of measurement error on results.©2014 AACR.
Lynch BM, Friedenreich CM, Winkler EA, Healy GN, Vallance JK, Eakin EG, Owen N. Associations of objectively assessed physical activity and sedentary time with biomarkers of breast cancer risk in postmenopausal women: findings from NHANES (2003-2006). Breast Cancer Res Treat. 2011 Nov;130(1):183-94. Epub 2011 May 8.

Physical activity reduces the risk of postmenopausal breast cancer through multiple inter-related biologic mechanisms; sedentary time may contribute additionally to this risk. We examined cross-sectional associations of objectively assessed physical activity and sedentary time with established biomarkers of breast cancer risk in a population-based sample of postmenopausal women. Accelerometer, anthropometric and laboratory data were available for 1,024 (n = 443 fasting) postmenopausal women in the U.S. National Health and Nutrition Examination Survey 2003-2006. Associations of quartiles of the accelerometer variables (moderate- to vigorous-intensity activity, light-intensity activity and sedentary time per day; average length of active and sedentary bouts) with the continuous biomarkers were assessed using linear regression models. Following adjustment for potential confounders, including sedentary time, moderate- to vigorous-intensity activity had significant (P < 0.05), inverse associations with all biomarker outcomes (body mass index, waist circumference, C-reactive protein, fasting plasma glucose, fasting insulin and homeostasis model assessment of insulin resistance). Light-intensity activity and sedentary time were significantly associated in fully adjusted models with all biomarkers except fasting glucose. Active bout length was associated with a smaller waist circumference and lower C-reactive protein levels, while sedentary bout length was associated with a higher BMI. The associations of objectively assessed moderate- to vigorous-intensity activity with breast cancer biomarkers are consistent with the established beneficial effects of self-reported exercise on breast cancer risk. Our findings further suggest that light-intensity activity may have a protective effect, and that sedentary time may independently contribute to breast cancer risk.
Lynch BM, White SL, Owen N, Healy GN, Chadban SJ, Atkins RC, Dunstan DW. Television viewing time and risk of chronic kidney disease in adults: the AusDiab Study. Ann Behav Med. 2010 Dec;40(3):265-74.

BACKGROUND: Television viewing time independent of physical activity is associated with a number of chronic diseases and related risk factors; however, its relationship with chronic kidney disease is unknown.PURPOSE: The purpose of this study is to examine the cross-sectional and prospective relationships of television viewing time with biomarkers of chronic kidney disease.METHODS: Participants of the Australian Diabetes, Obesity and Lifestyle Study attended the baseline (n?=?10,847) and 5-year follow-up (n?=?6,293) examination.RESULTS: Television viewing was significantly associated with increased odds of prevalent albuminuria and low estimated glomerular filtration rate. In the gender-stratified analyses this pattern was seen for men, but not for women. In the longitudinal analyses, odds of de novo albuminuria and low estimated glomerular filtration rate were increased only in unadjusted models.CONCLUSIONS: Television viewing time may be directly related to markers of chronic kidney disease and through intertwined associated risk factors such as diabetes, hypertension, and obesity.
Lynch BM. Sedentary behavior and cancer: a systematic review of the literature and proposed biological mechanisms. Cancer Epidemiol Biomarkers Prev. 2010 Nov;19(11):2691-709. Epub 2010 Sep 10.

BACKGROUND: Sedentary behavior (prolonged sitting or reclining characterized by low energy expenditure) is associated with adverse cardiometabolic profiles and premature cardiovascular mortality. Less is known for cancer risk. The purpose of this review is to evaluate the research on sedentary behavior and cancer, to summarize possible biological pathways that may underlie these associations, and to propose an agenda for future research.METHODS: Articles pertaining to sedentary behavior and (a) cancer outcomes and (b) mechanisms that may underlie the associations between sedentary behavior and cancer were retrieved using Ovid and Web of Science databases.RESULTS: The literature review identified 18 articles pertaining to sedentary behavior and cancer risk, or to sedentary behavior and health outcomes in cancer survivors. Ten of these studies found statistically significant, positive associations between sedentary behavior and cancer outcomes. Sedentary behavior was associated with increased colorectal, endometrial, ovarian, and prostate cancer risk; cancer mortality in women; and weight gain in colorectal cancer survivors. The review of the literature on sedentary behavior and biological pathways supported the hypothesized role of adiposity and metabolic dysfunction as mechanisms operant in the association between sedentary behavior and cancer.CONCLUSIONS: Sedentary behavior is ubiquitous in contemporary society; its role in relation to cancer risk should be a research priority. Improving conceptualization and measurement of sedentary behavior is necessary to enhance validity of future work. Impact: Reducing sedentary behavior may be a viable new cancer control strategy.©2010 AACR.
Manini TM, Everhart JE, Patel KV, Schoeller DA, Colbert LH, Visser M, Tylavsky F, Bauer DC, Goodpaster BH, Harris TB. Daily activity energy expenditure and mortality among older adults. JAMA. 2006 Jul 12;296(2):171-9.

CONTEXT: Exercise is associated with mortality benefits but simply expending energy through any activity in an individual’s free-living environment may confer survival advantages.OBJECTIVE: To determine whether free-living activity energy expenditure is associated with all-cause mortality among older adults.DESIGN, SETTING, AND PARTICIPANTS: Free-living activity energy expenditure was assessed in 302 high-functioning, community-dwelling older adults (aged 70-82 years). Total energy expenditure was assessed over 2 weeks using doubly labeled water. Resting metabolic rate was measured using indirect calorimetry and the thermic effect of meals was estimated at 10% of total energy expenditure. Free-living activity energy expenditure was calculated as: (total energy expenditure x 0.90) – resting metabolic rate. Participants were followed up over a mean of 6.15 years (1998-2006).MAIN OUTCOME MEASURES: Free-living activity energy expenditure (3 tertiles: low, <521 kcal/d; middle, 521-770 kcal/d; high, >770 kcal/d) and all-cause mortality.RESULTS: Fifty-five participants (18.2%) died during follow-up. As a continuous risk factor, an SD increase in free-living activity energy expenditure (287 kcal/d) was associated with a 32% lower risk of mortality after adjusting for age, sex, race, study site, weight, height, percentage of body fat, and sleep duration (hazard ratio, 0.68; 95% confidence interval, 0.48-0.96). Using the same adjustments, individuals in the highest tertile of free-living activity energy expenditure were at a significantly lower mortality risk compared with the lowest tertile (hazard ratio, 0.31; 95% confidence interval, 0.14-0.69). Absolute risk of death was 12.1% in the highest tertile of activity energy expenditure vs 24.7% in the lowest tertile; absolute risks were similar to these for tertiles of physical activity level. The effect of free-living activity energy expenditure changed little after further adjustment for self-rated health, education, prevalent health conditions, and smoking behavior. According to self-reports, individuals expending higher levels of free-living activity energy were more likely to work for pay (P = .004) and climb stairs (P = .01) but self-reported high-intensity exercise, walking for exercise, walking other than for exercise, volunteering, and caregiving did not differ significantly across the activity energy expenditure tertiles.CONCLUSIONS: Objectively measured free-living activity energy expenditure was strongly associated with lower risk of mortality in healthy older adults. Simply expending energy through any activity may influence survival in older adults.Comment inJAMA. 2006 Jul 12;296(2):216-8.
Manns PJ, Dunstan DW, Owen N, Healy GN. Addressing the Nonexercise Part of the Activity Continuum: A More Realistic and Achievable Approach to Activity Programming for Adults With Mobility Disability? Phys Ther. 2012 Jan 12. [Epub ahead of print]

Participation in physical activity is fundamental for the maintenance of metabolic health and the prevention of major chronic diseases, particularly type 2 diabetes and cardiovascular disease. A whole-of-day approach to physical activity promotion is increasingly advocated and includes not only increasing moderate-intensity physical activity but also reducing sedentary time and increasing light-intensity activity (the “nonexercise” part of the activity continuum). This whole-of-day approach to tackling the challenge of inactivity may be particularly relevant for adults with mobility disabilities, who are among the most inactive segment of the population. Focusing on nonexercise activity by striving to reduce sedentary time and increase light-intensity activity may be a more successful place to begin to change behavior in someone with mobility disability. This article discusses what is known about the metabolic health consequences of sedentary behavior and light-intensity activity in adults with and without mobility disability. The concept of inactivity physiology is presented, along with possible applications or evidence from studies with adults with mobility disability. Mobility disability discussions and examples focus on stroke and spinal cord injury. Finally, clinical implications and future research directions related to sedentary behavior in adults with mobility disability are discussed.
Marshall SJ, Gorely T, Biddle SJ. A descriptive epidemiology of screen-based media use in youth: a review and critique. J Adolesc. 2006 Jun;29(3):333-49. Epub 2005 Oct 21.

The purpose of this systematic review was to (i) estimate the prevalence and dose of television (TV) viewing, video game playing and computer use, and (ii) assess age-related and (iii) secular trends in TV viewing among youth (< or = 18 yr). Ninety studies published in English language journals between 1949 and 2004 were included, presenting data from 539 independent samples (the unit of analysis). Results suggest contemporary youth watch on average 1.8-2.8 h of TV per day, depending on age and gender. Most (66%) are “low users” (< 2 h day(-1)) of TV but 28% watch more than 4 h day(-1). Boys and girls with access to video games spend approximately 60 and 23 min day(-1), respectively, using this technology. Computer use accounts for an additional 30 min day(-1). Age-specific data suggest TV viewing decreases during adolescence, but those considered “high users” at young ages are likely to remain high users when older. For children with access to a television set, the number of hours spent viewing does not appear to have increased over the past 50 years.
Marshall SJ, Ramirez E. Reducing Sedentary Behavior: A New Paradigm in Physical Activity Promotion Am. J. Lifestyle Med. 2011;DOI: 10.1177/1559827610395487.

There is growing interest in the role of sedentary behavior as a risk factor for poor health, independent of physical activity (PA). To guide the spectrum of descriptive, analytic, and intervention studies on sedentary behavior, the authors advocate a behavioral epidemiology framework. This 5-phase framework is useful because it outlines a series of sequential stages important for developing, evaluating, and diffusing interventions to reduce sedentary behavior and improve population health. Studies of sedentary behavior and health outcomes (phase I) have found consistent evidence that excessive use of screen-based media is linked to overweight and obesity in children, and there is some evidence among adults that overall sedentary time is associated with risk factors for cardiometabolic disease, some cancers, and mortality. Biological mechanisms to explain possible relationships have started to emerge but are mostly based on animal models. Obtaining valid and reliable measurements of sedentary behavior (phase II) remains a research priority because self-reports are prone to recall bias, and it appears that sedentary habits do not appear to be well represented by measures of individual behaviors such as TV viewing. Studies have identified few modifiable correlates of sedentary behavior (phase III), although research appears to be limited to studies of TV viewing or to scenarios in which sedentary behavior is defined as an absence of PA. Rigorous intervention research (phase IV) has focused almost exclusively on reducing self-reported TV viewing among children and adolescents, and there is consistent evidence that these interventions are efficacious. There appear to be no interventions focused exclusively on reducing sedentary behavior of adults. Translation studies (phase V) are absent because the underlying evidence is still emerging. Future research should focus on examining causal associations between sedentary behavior and health, developing objective measures of domain-specific sitting time, and identifying modifiable correlates of sedentary behavior that can be used as leverage points for behavioral interventions.
Martinez-Gomez D, Rey-López JP, Chillón P, Gómez-Martínez S, Vicente-Rodríguez G, Martín-Matillas M, Garcia-Fuentes M, Delgado M, Moreno LA, Veiga OL, Eisenmann JC, Marcos A; AVENA Study Group. Excessive TV viewing and cardiovascular disease risk factors in adolescents. The AVENA cross-sectional study. BMC Public Health. 2010 May 25;10:274.

BACKGROUND: Excessive television (TV) viewing might play an important role in the development of cardiovascular disease (CVD). The aim of this study was to examine the independent associations between TV viewing and CVD risk factors in adolescents.METHODS: A sample of 425 adolescents, aged 13- to 18.5-year-old, was included in this study. Body mass index (BMI), waist circumference (WC), glucose, total cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, apolipoprotein (apo) A-1, apo B-100, and lipoprotein(a) levels were determined. A composite CVD risk score was computed based on age-, sex-, sexual maturation- and race-standardized triglycerides, HDL-cholesterol, LDL-cholesterol and glucose. TV viewing was self-reported.RESULTS: Two hundred and twenty-five adolescents (53%) who spent >3 hrs/day watching TV were considered as the “high TV viewing” group. Ninety-nine adolescents (23%) from the total sample were classified as overweight according to International age- and sex-specific BMI values. The high TV viewing group had significantly less favorable values of HDL-cholesterol, glucose, apo A1 and CVD score, independent of age, sex, sexual maturation, race and weight status. There was a significant interaction effect of TV viewing x weight status (P = 0.002) on WC, and the negative influence of TV viewing on WC persisted in the overweight group (P = 0.031) but was attenuated in non-overweight adolescents (P > 0.05).CONCLUSION: Excessive TV viewing seems to be related to an unfavorable CVD risk factors profile in adolescence. Reducing TV viewing in overweight adolescents might be beneficial to decrease abdominal body fat.
Matthews CE, Chen KY, Freedson PS, Buchowski MS, Beech BM, Pate RR, Troiano RP. Amount of time spent in sedentary behaviors in the United States, 2003-2004. Am J Epidemiol. 2008 Apr 1;167(7):875-81. Epub 2008 Feb 25.

Sedentary behaviors are linked to adverse health outcomes, but the total amount of time spent in these behaviors in the United States has not been objectively quantified. The authors evaluated participants from the 2003-2004 National Health and Nutrition Examination Survey aged >/=6 years who wore an activity monitor for up to 7 days. Among 6,329 participants with at least one 10-hour day of monitor wear, the average monitor-wearing time was 13.9 hours/day (standard deviation, 1.9). Overall, participants spent 54.9% of their monitored time, or 7.7 hours/day, in sedentary behaviors. The most sedentary groups in the United States were older adolescents and adults aged >/=60 years, and they spent about 60% of their waking time in sedentary pursuits. Females were more sedentary than males before age 30 years, but this pattern was reversed after age 60 years. Mexican-American adults were significantly less sedentary than other US adults, and White and Black females were similarly sedentary after age 12 years. These data provide the first objective measure of the amount of time spent in sedentary behavior in the US population and indicate that Americans spend the majority of their time in behaviors that expend very little energy.
Matthews CE, George SM, Moore SC, Bowles HR, Blair A, Park Y, Troiano RP, Hollenbeck A, Schatzkin A. Amount of time spent in sedentary behaviors and cause-specific mortality in US adults. Am J Clin Nutr. 2012 Jan 4. [Epub ahead of print]

BACKGROUND: Sedentary behaviors predominate modern life, yet we do not fully understand the adverse effects of these behaviors on mortality after considering the benefits of moderate-vigorous physical activity (MVPA).OBJECTIVE: We tested the hypotheses that higher amounts of overall sitting time and television viewing are positively associated with mortality and described the independent and combined effects of these sedentary behaviors and MVPA on mortality.DESIGN: In the NIH-AARP Diet and Health Study, we examined 240,819 adults (aged 50-71 y) who did not report any cancer, cardiovascular disease, or respiratory disease at baseline. Mortality was ascertained over 8.5 y.RESULTS: Sedentary behaviors were positively associated with mortality after adjustment for age, sex, education, smoking, diet, race, and MVPA. Participants who reported the most television viewing (?7 h compared with <1 h/d) were at greater risk of all-cause (HR: 1.61; 95% CI: 1.47, 1.76), cardiovascular (HR: 1.85; 95% CI: 1.56, 2.20), and cancer (HR: 1.22; 95% CI: 1.06, 1.40) mortality after adjustment for MVPA. Overall sitting was associated with all-cause mortality. Even among adults reporting high levels of MVPA (>7 h/wk), high amounts of television viewing (?7 h/d) remained associated with increased risk of all-cause (HR: 1.47; 95% CI: 1.20, 1.79) and cardiovascular (HR: 2.00; 95% CI: 1.33, 3.00) mortality compared with those reporting the least television viewing (<1 h/d).CONCLUSIONS: Time spent in sedentary behaviors was positively associated with mortality, and participation in high levels of MVPA did not fully mitigate health risks associated with prolonged time watching television. Adults should be encouraged to reduce time spent in sedentary behaviors, when possible, and to participate in MVPA at recommended levels. The NIH-AARP Diet and Health Study was registered at as NCT00340015.
Matthews CE, Jurj AL, Shu XO, Li HL, Yang G, Li Q, Gao YT, Zheng W. Influence of exercise, walking, cycling, and overall nonexercise physical activity on mortality in Chinese women. Am J Epidemiol. 2007 Jun 15;165(12):1343-50. Epub 2007 May 2.

This investigation described the effects of exercise, walking, and cycling for transportation, as well as the effect of overall nonexercise physical activity, on mortality in the Shanghai Women’s Health Study (1997-2004). Women without heart disease, stroke, or cancer were followed for an average of 5.7 years (n = 67,143), and there were 1,091 deaths from all causes, 537 deaths from cancer, and 251 deaths from cardiovascular diseases. Information about physical activity and relevant covariates was obtained by interview. Proportional hazards models were used to estimate adjusted hazard ratios and 95% confidence intervals. Exercise and cycling for transportation were both inversely and independently associated with all-cause mortality (p(trend) < 0.05), but walking for transportation was less strongly associated with reduced risk (p(trend) = 0.07). Women reporting no regular exercise but who reported 10 or more metabolic equivalent (MET)-hours/day of nonexercise activity were at 25-50% reduced risk (p(trend) < 0.01) relative to less active women (0-9.9 MET-hours/day). Among women reporting the least nonexercise activity (0-9.9 MET-hours/day) but reporting regular exercise participation, exercise was associated with reduced mortality (hazard ratio = 0.78, 95% confidence interval: 0.62, 0.99). These findings add new evidence that overall physical activity levels are an important determinant of longevity, and that health benefit can be obtained through an active lifestyle, exercise, or combinations of both.Comment inAm J Epidemiol. 2007 Dec 1;166(11):1355-6. Am J Epidemiol. 2007 Jun 15;165(12):1351-3; discussion 1354-5.
Maureen C Ashe, Meghan Winters, Christiane A Hoppmann, Martin G Dawes, Paul A Gardiner, Lora M Giangregorio, Kenneth M Madden, Megan M McAllister, Gillian Wong, Joseph H Puyat, Joel Singer, Joanie Sims-Gould, Heather A McKay “Not just another walking program”: Everyday Activity Supports You (EASY) model—a randomized pilot study for a parallel randomized controlled trial Pilot and Feasibility Studies. 2015;1(1):4
McCann BS, Warnick GR, Knopp RH. Changes in plasma lipids and dietary intake accompanying shifts in perceived workload and stress. Psychosom Med. 1990 Jan-Feb;52(1):97-108.

Plasma lipids, dietary intake, and self-reported stress and workload were assessed in 14 employees twice before major work deadlines (high workload), and once during a comparatively quiescent period of work (low workload). Increases in self-reported stress and workload between the high and low workload periods were significantly positively associated with increases in plasma total cholesterol, although lipid levels were not increased in the group as a whole during the high workload periods. Dietary intake of calories, total fat, and percentage of calories from fat were significantly higher during high workload during a period of high workload is associated with elevated total cholesterol and that dietary intake of foods which raise cholesterol levels is also increased. Further studies of larger groups of subjects may be required to show a frank increase in cholesterol with increased workload.
Mickle KJ, Cliff DP, Munro BJ, Okely AD, Steele JR Relationship between plantar pressures, physical activity and sedentariness among preschool children. Journal of Science & Medicine in Sport, 2011;14:36-41

It has been speculated that high plantar pressures might cause foot pain and discomfort which, in turn, may discourage children from being physically active and result in them spending more time in sedentary activities. The purpose of this study was to determine whether plantar pressure distributions generated by preschool children were correlated with objectively measured time spent in physical activity and sedentary behaviour. Dynamic plantar pressures were measured for 33 preschool children (age=4.3±0.6 years; height=1.06±0.1 m; mass=18.4±2.9 kg; 17 boys) as they walked across an emed AT-4 pressure platform. Physical activity was objectively assessed using MTI ActiGraph accelerometers. Total physical activity (counts per minute), percentage of time spent in moderate-to-vigorous physical activity (MVPA), light activity and sedentary behaviour were then calculated. Peak pressures across the heel were found to significantly correlate with total physical activity (r=-0.53; p=0.03) and time in MVPA (r=-0.47; p=0.05) in boys. Similarly, the correlation data suggested that girls who generated higher peak pressures in the toe region spent more time in sedentary behaviour (r=0.53; p=0.04). As high plantar pressures appear to be a potential negative correlate of physical activity and sedentary behaviour, it is recommended that further research be conducted to design, test and evaluate the potential of interventions to reduce plantar pressures in inactive children so they can enjoy the benefits associated with participating in a more active lifestyle.
Mitchell JA, Pate RR, Beets MW, Nader PR. Time spent in sedentary behavior and changes in childhood BMI: a longitudinal study from ages 9 to 15 years. Int J Obes (Lond). 2012 Mar 20. doi: 10.1038/ijo.2012.41. [Epub ahead of print]

Objective:To determine if time spent in objectively measured sedentary behavior is associated with a change in body mass index (BMI) between ages 9 and 15 years, adjusting for moderate-to-vigorous physical activity (MVPA).Design:Prospective observational study of children at ages 9 (2000), 11 (2002), 12 (2003) and 15 years (2006). Longitudinal quantile regression was used to model the influence of predictors on changes at the 10th, 25th, 50th, 75th and 90th BMI percentiles over time.Subjects:Participants were enrolled in the National Institute of Child Health and Human Development (NICHD) Study of Early Child Care and Youth Development and include both boys and girls (n=789).Measurements:Objectively measured BMI (kg?m(-2)) was the outcome variable and objectively measured sedentary behavior was the main predictor. Adjustment was also made for MVPA, gender, race, maternal education, hours of sleep and healthy eating index.Results:Increases in BMI were observed at all percentiles, with the greatest increase observed at the 90th BMI percentile. Spending more time in sedentary behavior (h per day) was associated with additional increases in BMI at the 90th, 75th and 50th BMI percentiles, independent of MVPA and the other covariates (90th percentile=0.59, 95% confidence interval (95% CI): 0.19-0.98?kg?m(-2); 75th percentile=0.48, 95% CI: 0.25-0.72?kg?m(-2); and 50th percentile=0.19, 95% CI: 0.05-0.33?kg?m(-2)). No associations were observed between sedentary behavior and changes at the 25th and 10th BMI percentiles.Conclusion:Sedentary behavior was associated with greater increases in BMI at the 90th, 75th and 50th BMI percentiles between ages 9 and 15 years, independent of MVPA. Preventing an increase in sedentary behavior from childhood to adolescence may contribute to reducing the number of children classified as obese.International Journal of Obesity advance online publication, 20 March 2012; doi:10.1038/ijo.2012.41.
Mitchell JA, Pate RR, Blair SN. Screen-Based Sedentary Behavior and Cardiorespiratory Fitness from Age 11 To 13. Med Sci Sports Exerc. 2012 Jan 3. [Epub ahead of print]

PURPOSE: To determine if time spent in screen-based sedentary behavior is associated with change in cardiorespiratory fitness (CRF) levels in children from age 11 to 13, adjusting for vigorous physical activity (VPA).METHODS: Participants were children (n=2,097) enrolled in the control arm of the HEALTHY Study, who performed 20m shuttle run tests at ages 11 and 13. Self-reported screen time was used as a measure of sedentary behavior. Longitudinal quantile regression was used to model the influence of predictors on changes at the 10, 25, 50, 75 and 90 shuttle run lap percentiles. Screen time (hrs/d) was the main predictor and adjustment was also made for VPA, body mass index and household education.RESULTS: In boys, more screen time was associated with fewer shuttle run laps completed from age 11 to 13 at the 25, 50 and 75 shuttle run lap percentiles; the strongest association was at the 75th shuttle run percentile (-0.57, 95% CI: -0.93 to -0.21). In girls, more screen time was associated with fewer shuttle run laps completed from age 11 to 13 at the 50, 75 and 90 shuttle run lap percentiles; the strongest association was at the 90 shuttle run percentile (-0.65, -1.01 to -0.30). Borderline negative associations were found between screen time and shuttle run laps at the 10 shuttle run percentile in boys and girls (-0.28, -0.57 to 0.01 and -0.17, -0.41 to 0.06, respectively).CONCLUSION: More screen time was associated with lower CRF from age 11 to 13, independent of VPA. However, the association was weakest at the lower tail of the CRF distribution.
Mitchell JA, Pate RR, Dowda M, Mattocks C, Riddoch C, Ness AR, Blair SN. A prospective study of sedentary behavior in a large cohort of youth. Med Sci Sports Exerc. 2012 Jun;44(6):1081-7.

PURPOSE: The study’s purpose was to describe longitudinal patterns of objectively measured sedentary behavior from age 12 to 16.METHODS: Children participating in the Avon Longitudinal Study of Parents and Children wore accelerometers for 1 wk at ages 12, 14, and 16. Participants included boys (n = 2591) and girls (n = 2845) living in a single geographic location in the United Kingdom (Bristol). Total minutes per day spent in sedentary behavior and time spent in blocks of sedentary behavior lasting 10-19, 20-29, and ?30 min are described. Growth curve models were used to determine the rate of change in sedentary behavior from age 12 to 16.RESULTS: At age 12, the boys and girls, on average, were sedentary for 418.0 ± 67.7 and 436.6 ± 64.0 min·d, respectively, and sedentary behavior increased over time to 468.0 ± 74.3 and 495.6 ± 68.9 min·d at age 14 and to 510.4 ± 76.6 and 525.4 ± 67.4 min·d at age 16. Growth curve analyses found that total sedentary behavior increased at a rate of 19.5 ± 0.7 and 22.8 ± 0.7 min·d·yr for the boys and girls, respectively. The absolute mean increase in total sedentary behavior (+92.4 and +88.8 min·d for the boys and girls, respectively) closely matched the mean decrease in light physical activity (-82.2 and -82.9 min·d for the boys and girls, respectively) from age 12 to 16. Time spent in continuous sedentary behavior lasting ?30 min increased by 121% from age 12 to 16.CONCLUSIONS: Sedentary behavior increased with age, at the expense of light physical activity. The increase in sedentary behavior lasting ?30 min in duration contributed greatly to the increase in total sedentary behavior.
MORRIS JN, HEADY JA, RAFFLE PA, ROBERTS CG, PARKS JW. Coronary heart-disease and physical activity of work. Lancet. 1953 Nov 21;265(6795):1053-7; contd.

[No abstract available.]
Murdey ID, Cameron N, Biddle SJ, Marshall SJ, Gorely T. Pubertal development and sedentary behaviour during adolescence. Ann Hum Biol. 2004 Jan-Feb;31(1):75-86.

BACKGROUND: Assessing time spent in sedentary behaviours in relation to pubertal status, anthropometric differences, and body image will improve insight into the prevalence and determinants of such behaviours during adolescence.AIM: The study aimed to investigate the effects of age, puberty, gender, body composition, and sleep on sedentary behaviour.PARTICIPANTS AND METHODS: Participants were 64 boys and 55 girls in Year 6 (10.0-10.9 years of age), Year 8 (12.0-12.9 years) and Year 10 (14.0-14.9 years). Body mass index and percentage body fat were calculated from anthropometric measures. Sedentary behaviour and sleep time were computed using momentary-time sampling. Body image was measured using the Children’s Physical Self-Perception Profile. Pubertal status was assessed from self-report of secondary sexual characteristics.RESULTS: After controlling for sleep time, no differences in sedentary time were seen for puberty onset or increased pubertal development. Correlations between pubertal status, body composition, and body image were stronger in girls than in boys. Correlations between body image and sedentary behaviour were not strong enough to infer behavioural choice differences.CONCLUSIONS: Reduced sleep time rather than changing body image and body composition during adolescence is associated with greater sedentary behaviour.
Murdey ID, Cameron N, Biddle SJ, Marshall SJ, Gorely T. Short-term changes in sedentary behaviour during adolescence: Project STIL (Sedentary Teenagers and Inactive Lifestyles). Ann Hum Biol. 2005 May-Jun;32(3):283-96.

HYPOTHESIS: Changes in body composition and body image during puberty will impact on sedentary behavioural choices.AIM: The study aimed to investigate the effects of changes in pubertal status, body composition and body image on changes in time spent being sedentary.PARTICIPANTS AND METHODS: Eighty-three school students aged 10-15 years were studied at 6-month intervals. BMI and percentage body fat (%BF) were calculated from anthropometric measures. Sedentary behaviour and sleep time were computed for weekday and weekend days using momentary-time-sampling diaries. Body image was measured using the Physical Self-Perception Profile for Children. Pubertal status was assessed from self-reported secondary sexual characteristics.RESULTS: During weekdays, boys’ sedentary behaviour increased by a significantly greater amount for those who increased pubertal level compared with those who did not. No significant correlations were found between changing pubertal status, body composition, and body image for either gender. For girls, but not boys, a significant amount of the variance of the change in weekend day sedentary behaviour was explained by changing %BF, independent of changing pubertal status.CONCLUSION: Only a part of the hypothesis was supported by these data. Changes in sedentary behaviour were not associated with behavioural choices triggered by body compositional changes.
Nelson ME, Rejeski WJ, Blair SN, Duncan PW, Judge JO, King AC, Macera CA, Castaneda-Sceppa C; American College of Sports Medicine; American Heart Association. Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association. Circulation. 2007 Aug 28;116(9):1094-105. Epub 2007 Aug 1.

OBJECTIVE: To issue a recommendation on the types and amounts of physical activity needed to improve and maintain health in older adults.PARTICIPANTS: A panel of scientists with expertise in public health, behavioral science, epidemiology, exercise science, medicine, and gerontology.EVIDENCE: The expert panel reviewed existing consensus statements and relevant evidence from primary research articles and reviews of the literature. Process: After drafting a recommendation for the older adult population and reviewing drafts of the Updated Recommendation from the American College of Sports Medicine (ACSM) and the American Heart Association (AHA) for Adults, the panel issued a final recommendation on physical activity for older adults.SUMMARY: The recommendation for older adults is similar to the updated ACSM/AHA recommendation for adults, but has several important differences including: the recommended intensity of aerobic activity takes into account the older adult’s aerobic fitness; activities that maintain or increase flexibility are recommended; and balance exercises are recommended for older adults at risk of falls. In addition, older adults should have an activity plan for achieving recommended physical activity that integrates preventive and therapeutic recommendations. The promotion of physical activity in older adults should emphasize moderate-intensity aerobic activity, muscle-strengthening activity, reducing sedentary behavior, and risk management.
Neuhaus M1, Healy GN, Fjeldsoe BS, Lawler S, Owen N, Dunstan DW, LaMontagne AD, Eakin EG. Iterative development of Stand Up Australia: a multi-component intervention to reduce workplace sitting. Int J Behav Nutr Phys Act. 2014 Feb 21;11:21. doi: 10.1186/1479-5868-11-21.

BACKGROUND: Sitting, particularly in prolonged, unbroken bouts, is widespread within the office workplace, yet few interventions have addressed this newly-identified health risk behaviour. This paper describes the iterative development process and resulting intervention procedures for the Stand Up Australia research program focusing on a multi-component workplace intervention to reduce sitting time.METHODS: The development of Stand Up Australia followed three phases. 1) Conceptualisation: Stand Up Australia was based on social cognitive theory and social ecological model components. These were operationalised via a taxonomy of intervention strategies and designed to target multiple levels of influence including: organisational structures (e.g. via management consultation), the physical work environment (via provision of height-adjustable workstations), and individual employees (e.g. via face-to-face coaching). 2) Formative research: Intervention components were separately tested for their feasibility and acceptability. 3) Pilot studies: Stand Up Comcare tested the integrated intervention elements in a controlled pilot study examining efficacy, feasibility and acceptability. Stand Up UQ examined the additional value of the organisational- and individual-level components over height-adjustable workstations only in a three-arm controlled trial. In both pilot studies, office workers’ sitting time was measured objectively using activPAL3 devices and the intervention was refined based on qualitative feedback from managers and employees.RESULTS: Results and feedback from participants and managers involved in the intervention development phases suggest high efficacy, acceptance, and feasibility of all intervention components. The final version of the Stand Up Australia intervention includes strategies at the organisational (senior management consultation, representatives consultation workshop, team champions, staff information and brainstorming session with information booklet, and supportive emails from managers to staff), environmental (height-adjustable workstations), and individual level (face-to-face coaching session and telephone support). Stand Up Australia is currently being evaluated in the context of a cluster-randomised controlled trial at the Department of Human Services (DHS) in Melbourne, Australia.CONCLUSIONS: Stand Up Australia is an evidence-guided and systematically developed workplace intervention targeting reductions in office workers’ sitting time.
Neuhaus M1, Healy GN2, Dunstan DW3, Owen N4, Eakin EG2. Workplace sitting and height-adjustable workstations: a randomized controlled trial. Am J Prev Med. 2014 Jan;46(1):30-40. doi: 10.1016/j.amepre.2013.09.009.

BACKGROUND: Desk-based office employees sit for most of their working day. To address excessive sitting as a newly identified health risk, best practice frameworks suggest a multi-component approach. However, these approaches are resource intensive and knowledge about their impact is limited.PURPOSE: To compare the efficacy of a multi-component intervention to reduce workplace sitting time, to a height-adjustable workstations-only intervention, and to a comparison group (usual practice).DESIGN: Three-arm quasi-randomized controlled trial in three separate administrative units of the University of Queensland, Brisbane, Australia. Data were collected between January and June 2012 and analyzed the same year.SETTING/PARTICIPANTS: Desk-based office workers aged 20-65 (multi-component intervention, n=16; workstations-only, n=14; comparison, n=14).INTERVENTION: The multi-component intervention comprised installation of height-adjustable workstations and organizational-level (management consultation, staff education, manager e-mails to staff) and individual-level (face-to-face coaching, telephone support) elements.MAIN OUTCOME MEASURES: Workplace sitting time (minutes/8-hour workday) assessed objectively via activPAL3 devices worn for 7 days at baseline and 3 months (end-of-intervention).RESULTS: At baseline, the mean proportion of workplace sitting time was approximately 77% across all groups (multi-component group 366 minutes/8 hours [SD=49]; workstations-only group 373 minutes/8 hours [SD=36], comparison 365 minutes/8 hours [SD=54]). Following intervention and relative to the comparison group, workplace sitting time in the multi-component group was reduced by 89 minutes/8-hour workday (95% CI=-130, -47 minutes; p<0.001) and 33 minutes in the workstations-only group (95% CI=-74, 7 minutes, p=0.285).CONCLUSIONS: A multi-component intervention was successful in reducing workplace sitting. These findings may have important practical and financial implications for workplaces targeting sitting time reductions.CLINICAL TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry 00363297.© 2013 American Journal of Preventive Medicine Published by American Journal of Preventive Medicine All rights reserved.
Otten JJ, Jones KE, Littenberg B, Harvey-Berino J. Effects of television viewing reduction on energy intake and expenditure in overweight and obese adults: a randomized controlled trial. Arch Intern Med. 2009 Dec 14;169(22):2109-15.

BACKGROUND: The average adult watches almost 5 hours of television (TV) per day, an amount associated with increased risks for obesity. This trial examines the effects of TV reduction on energy intake (EI), energy expenditure (EE), energy balance, body mass index (BMI), (calculated as weight in kilograms divided by height in meters squared), and sleep in overweight and obese adults.METHODS: Randomized controlled trial of 36 adults with a BMI of 25 to 50 who self-reported a minimum of 3 h/d of TV viewing. Participants were enrolled in home-based protocols from January through July 2008. After a 3-week observation phase, participants were stratified by BMI and randomized to an observation-only control group (n = 16) or an intervention group (n = 20) for 3 additional weeks. The intervention consisted of reducing TV viewing by 50% of each participant’s objectively measured baseline enforced by an electronic lock-out system.RESULTS: Although not statistically significant, both groups reduced their EI (-125 kcal/d [95% CI, -303 to 52] vs -38 [95% CI, -265 to 190]) (P = .52) for intervention and control group participants, respectively, where CI indicates confidence interval. The intervention group significantly increased EE (119 kcal/d [95% CI, 23 to 215]) compared with controls (-95 kcal/d [95% CI, -254 to 65]) (P = .02). Energy balance was negative in the intervention group between phases (-244 kcal/d [95% CI, -459 to -30]) but positive in controls (57 kcal/d [95% CI, -216 to 330]) (P = .07). The intervention group showed a greater reduction in BMI (-0.25 [95% CI, -0.45 to -0.05] vs -0.06 [95% CI, -0.43 to 0.31] in controls) (P = .33). There was no change in sleep.CONCLUSION: Reducing TV viewing in our sample produced a statistically significant increase in EE but no apparent change in EI after 3 weeks of intervention. Trial Registration Identifier: NCT00622050.Comment inArch Intern Med. 2009 Dec 14;169(22):2124-7. Arch Intern Med. 2010 Jul 12;170(13):1173-4; author reply 1174.
Owen N, Healy GN, Matthews CE, Dunstan DW. Too much sitting: the population health science of sedentary behavior. Exerc Sport Sci Rev. 2010 Jul;38(3):105-13.

Even when adults meet physical activity guidelines, sitting for prolonged periods can compromise metabolic health. Television (TV) time and objective measurement studies show deleterious associations, and breaking up sedentary time is beneficial. Sitting time, TV time, and time sitting in automobiles increase premature mortality risk. Further evidence from prospective studies, intervention trials, and population-based behavioral studies is required.Comment inExerc Sport Sci Rev. 2010 Jul;38(3):101-2.
Owen N, Sugiyama T, Eakin EE, Gardiner PA, Tremblay MS, Sallis JF. Adults' sedentary behavior determinants and interventions. Am J Prev Med. 2011 Aug;41(2):189-96.

Research is now required on factors influencing adults’ sedentary behaviors, and effective approaches to behavioral-change intervention must be identified. The strategies for influencing sedentary behavior will need to be informed by evidence on the most important modifiable behavioral determinants. However, much of the available evidence relevant to understanding the determinants of sedentary behaviors is from cross-sectional studies, which are limited in that they identify only behavioral “correlates.” As is the case for physical activity, a behavior- and context-specific approach is needed to understand the multiple determinants operating in the different settings within which these behaviors are most prevalent. To this end, an ecologic model of sedentary behaviors is described, highlighting the behavior settings construct. The behaviors and contexts of primary concern are TV viewing and other screen-focused behaviors in domestic environments, prolonged sitting in the workplace, and time spent sitting in automobiles. Research is needed to clarify the multiple levels of determinants of prolonged sitting time, which are likely to operate in distinct ways in these different contexts. Controlled trials on the feasibility and efficacy of interventions to reduce and break up sedentary behaviors among adults in domestic, workplace, and transportation environments are particularly required. It would be informative for the field to have evidence on the outcomes of “natural experiments,” such as the introduction of nonseated working options in occupational environments or new transportation infrastructure in communities.Copyright © 2011 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.
Patel MJ, Slentz CA, Kraus WE. Metabolic Deterioration of the Sedentary Control Group in Clinical Trials. J Appl Physiol. 2011 Jul 21. [Epub ahead of print]

Randomized clinical trials of exercise training regimens in sedentary individuals have provided a mechanistic understanding of the long-term health benefits and consequences of physical activity and inactivity. The sedentary control periods from these trials have provided evidence of the progressive metabolic deterioration that results from as little as four to six months of continuing a physically inactive lifestyle. These clinical trials have also demonstrated that only a modest amount of physical activity is required to prevent this metabolic deterioration, and this amount of physical activity is consistent with current physical activity recommendations (150 minutes per week of moderate intensity physical activity per week). These recommendations have been issued to the general population for a vast array of health benefits. While greater adherence to these recommendations should result in substantial improvements in the health of the population, these recommendations still remain inadequate for many individuals. An individual’s physical activity requirements are influenced by such factors as an individual’s diet, non-exercise physical activity patterns, genetic profile, and medications. Improving the understanding of how these factors influence an individual’s physical activity requirements will help advance the field and help move the field toward the development of more personalized physical activity recommendations.
Prapavessis, H., Gaston, A., & De Jesus, S . The Theory of Planned Behaviour as a model for understanding sedentary behaviour. Prapavessis, H., Gaston, A., & De Jesus, S (2015). The Theory of Planned Behaviour as a model for understanding sedentary behaviour. Psychology of Sport and Exercise, 19, 23-32.

Objectives: Sedentary time has emerged as an independent risk factor for numerous adverse health outcomes. However, little is known about the social-cognitive correlates of sedentary behavior. The purpose of this study was to provide preliminary evidence for the factor structure and composition of sedentary derived Theory of Planned Behavior (TPB) constructs and to determine the utility of these constructs in predicting sedentary intention and sedentary time. Method: Twenty-three items were created to assess attitudes, subjective norms (SN), perceived behav- ioral control (PBC), and intention with respect to time spent being sedentary. Using a web-based survey, 372 adults completed a modified Sedentary Behavior Questionnaire and were then randomised to one of three TPB questionnaire packages: general, weekday, and weekend. Weekday and weekend participants completed items for work/school (less-volitional) and leisure/recreation (volitional) activities separately, resulting in five TPB models being analyzed: general, weekday work/school, weekday leisure/recreation, weekend work/school, and weekend leisure/recreation. Results: Irrespective of model, items grouped into coherent factors consistent with TPB and explained 9 e58% and 8e43% of the variance in intention and behavior, respectively. The strongest and most consistent predictor of intention and behavior were SN and intentions, respectively. Mediation analyses indicated that attitudes consistently affected sedentary time through intention. Conclusions: There is growing evidence that the TPB is a useful framework for understanding sedentarism.
Prentice AM, Black AE, Coward WA, Cole TJ. Energy expenditure in overweight and obese adults in affluent societies: an analysis of 319 doubly-labelled water measurements. Eur J Clin Nutr. 1996 Feb;50(2):93-7.

OBJECTIVES: To describe the relationship between graded levels of obesity and free-living energy expenditure in men and women in affluent societies.DESIGN: Analysis of 319 measurements of energy expenditure in adults aged 18-64 years. The variables analysed were: total energy expenditure (TEE, assessed by the doubly-labelled water method); measured basal metabolic rate (BMR); activity energy expenditure (AEE, derived as TEE-BMR); and physical activity level (PAL, derived as TEE/BMR). Results were analysed according to four categories of body mass index (BMI): < 25.0, 25.0-29.9, 30.0-35.0 and > 35.0 kg/m2.RESULTS: TEE increased steadily with increasing BMI (9.5 to 13.5 MJ/d in women, 12.9 to 17.5 MJ/d in men, ANOVA, P < 0.0001 for both sexes). BMR also increased (5.7 to 8.2 MJ/d in women, 7.2 to 11.6 MJ/d in men, P < 0.0001 for both). AEE increased steadily in women (3.8 to 5.3 MJ/d, P < 0.0003), but in men increased up to the third BMI category (5.7 to 7.5 MJ/d, n.s.) and then declined in the most obese group (5.9 MJ/d, n.s.). The increases in energy expenditure were not in direct proportion to body weight since, when expressed per kg, both TEE and AEE declined significantly with increasing BMI. PAL remained quite constant across the three lowest BMI groups, indicating similar levels of physical activity. There was a non-significant decrease in PAL in the most obese men and women.CONCLUSIONS: This analysis confirms that habitual energy expenditure is substantially and progressively raised in obesity. It contradicts the claim, based on self-reported food intake, that obesity develops and is maintained in spite of very low levels of energy intake. The analysis suggests that, except in massive obesity, patterns of physical activity are quite similar at different levels of BMI. This does not exclude the possibility that an inactive lifestyle may be an important general risk factor for the development of obesity.
Prince SA, Reed JL, McFetridge C, Tremblay MS, Reid RD. Correlates of sedentary behaviour in adults: a systematic review Prince SA, Reed JL, McFetridge C, Tremblay MS, Reid RD. Correlates of sedentary behaviour in adults: a systematic review. Obes Rev. 2017 May 19.

OBJECTIVE: The objective of this study was to systematically review evidence to identify intrapersonal, social environmental, physical environmental and policy correlates of sedentary behaviour (SB) among adults. METHODS: Six databases were searched to identify studies that reported on intrapersonal, social, physical environmental and/or policy correlates of SB across domains (i.e. occupational, leisure and transportation) in adults (mean ? 18 years old). Subgroup differences (sex, age, disease status, publication status and date, weekdays vs. weekend) were examined. Risk of bias was assessed, and a qualitative synthesis completed. RESULTS: Searching identified 22,779 articles; 257 were used in the analysis. Most studies used self-reported SB and were cross-sectional. The most studied domain of SB and correlate was leisure and intrapersonal, respectively. Consistent evidence found positive relationships between full-time employment and higher transportation and lower leisure SB; higher income/socioeconomic status and greater transportation and occupation SB; living in more urban areas and greater sitting time and total SB; ownership of televisions and greater leisure SB; and, active workstations and lower occupational SB.CONCLUSIONS: The review identifies the need for longitudinal studies, as well as further research on factors in the physical, social and policy environments. The review also recognizes the need to standardize methodology for collecting, defining and reporting SB and correlates.
Proper KI, Singh AS, van Mechelen W, Chinapaw MJ. Sedentary behaviors and health outcomes among adults: a systematic review of prospective studies. Am J Prev Med. 2011 Feb;40(2):174-82.

CONTEXT: Nowadays, people spend a substantial amount of time per day on sedentary behaviors and it is likely that the time spent sedentary will continue to rise. To date, there is no review of prospective studies that systematically examined the relationship between diverse sedentary behaviors and various health outcomes among adults.PURPOSE: This review aimed to systematically review the literature as to the relationship between sedentary behaviors and health outcomes considering the methodologic quality of the studies.EVIDENCE ACQUISITION: In February 2010, a search for prospective studies was performed in diverse electronic databases. After inclusion, in 2010, the methodologic quality of each study was assessed. A best-evidence synthesis was applied to draw conclusions.EVIDENCE SYNTHESIS: 19 studies were included, of which 14 were of high methodologic quality. Based on inconsistency in findings among the studies and lack of high-quality prospective studies, insufficient evidence was concluded for body weight-related measures, CVD risk, and endometrial cancer. Further, moderate evidence for a positive relationship between the time spent sitting and the risk for type 2 diabetes was concluded. Based on three high-quality studies, there was no evidence for a relationship between sedentary behavior and mortality from cancer, but strong evidence for all-cause and CVD mortality.CONCLUSIONS: Given the trend toward increased time in sedentary behaviors, additional prospective studies of high methodologic quality are recommended to clarify the causal relationships between sedentary behavior and health outcomes. Meanwhile, evidence to date suggests that interventions aimed at reducing sedentary behavior are needed.Copyright © 2011 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.
Pulsford RM, Cortina-Borja M, Rich C, Kinnafick FE, Dezateux C, Griffiths LJ. Actigraph accelerometer-defined boundaries for sedentary behaviour and physical activity intensities in 7 year old children. PLoS One. 2011;6(8):e21822. Epub 2011 Aug 11.

BACKGROUND: Accurate objective assessment of sedentary and physical activity behaviours during childhood is integral to the understanding of their relation to later health outcomes, as well as to documenting the frequency and distribution of physical activity within a population.PURPOSE: To calibrate the Actigraph GT1M accelerometer, using energy expenditure (EE) as the criterion measure, to define thresholds for sedentary behaviour and physical activity categories suitable for use in a large scale epidemiological study in young children.METHODS: Accelerometer-based assessments of physical activity (counts per minute) were calibrated against EE measures (kcal x kg(-1) x hr(-1)) obtained over a range of exercise intensities using a COSMED K4b(2) portable metabolic unit in 53 seven-year-old children. Children performed seven activities: lying down viewing television, sitting upright playing a computer game, slow walking, brisk walking, jogging, hopscotch and basketball. Threshold count values were established to identify sedentary behaviour and light, moderate and vigorous physical activity using linear discriminant analysis (LDA) and evaluated using receiver operating characteristic (ROC) curve analysis.RESULTS: EE was significantly associated with counts for all non-sedentary activities with the exception of jogging. Threshold values for accelerometer counts (counts x minute(-1)) were <100 for sedentary behaviour and ?2240, ?3840 and ?3841 for light, moderate and vigorous physical activity respectively. The area under the ROC curves for discrimination of sedentary behaviour and vigorous activity were 0.98. Boundaries for light and moderate physical activity were less well defined (0.61 and 0.60 respectively). Sensitivity and specificity were higher for sedentary (99% and 97%) and vigorous (95% and 91%) than for light (60% and 83%) and moderate (61% and 76%) thresholds.CONCLUSION: The accelerometer cut points established in this study can be used to classify sedentary behaviour and to distinguish between light, moderate and vigorous physical activity in children of this age.
R Viir, A Virkus, K Laiho, K Rajaleid, A Selart Trapezius muscle tone and viscoelastic properties in sitting and supine positions SJWEH Suppl 2007;(3):76–80

Objectives: In this study, the aim was to use the upper trapezius muscle as a representative of the musculoskeletal support system to determine the effect of changing from a sitting position to a lying position on muscle tension and whether this change could be useful in the prevention of musculoskeletal complaints. Methods: Fifteen healthy right-handed female computer operators participated in this study. Myometric mea- surements of the upper trapezius muscle on both sides of the body were recorded for the participants while they were in a sitting position and then again in a supine position. Results: Changing from a sitting position to a supine position reduced the tone and stiffness by up to one- fifth—important characteristics of the support function—in the upper trapezius muscle. Conclusions: The change in the tone and stiffness of the trapezius muscle is of significance to the well-being of sedentary workers, particularly computer-terminal operators. Including recommended regular breaks of brief periods of simple, unchallenging movements while in a supine position should enhance their recovery from prolonged sitting because the support requirement on the muscles is lessened.
Ragnar Viir,a Alar Veraksitšb aR. Viir. Ragnar Viir Limited Partnership, Sorsavuorenkatu 8 B 41, 00810 Helsinki, Finland. bA. Veraksitš. Department of Physiology University of Tartu, 19 Ravila Street, 50411 Tartu, Estonia. Corresponding author: Ragnar Viir (e-mail:, There is a reply by Tremblay (2012), published in this issue. Published on the web 20 September 2012. Discussion of "Letter to the Editor: Standardized use of the terms sedentary and sedentary behaviours" - Sitting and reclining are different states.

Regan A, Heary C. Patterns of sedentary behaviours in Irish female adolescents. J Adolesc. 2013 Apr;36(2):269-78. doi: 10.1016/j.adolescence.2012.11.002. Epub 2012 Dec 20.

Engagement in excessive sedentary behaviour represents a health risk for adolescents. The current study aimed to investigate patterns of sedentary behaviour amongst Irish female adolescents aged between 15 and 19 years old. 314 adolescents completed a questionnaire on their sedentary behaviour habits, health behaviours (physical activity, smoking, and alcohol use), enjoyment of sedentary behaviour, value on health, and sedentary facilitators in their home. Parents provided information on parental education, the child’s weight and height, and parental sedentary behaviour habits. Cluster analysis found that five distinct sedentary clusters existed in this sample: Unproductive/Social Sedentary, Reading/Productive Behaviours, Mixed Sedentary Interests, Restricted Interests/High Television, and Academic Sedentary. The clusters differed on smoking and alcohol use, enjoyment of sedentary behaviour, and parental engagement in sedentary behaviour. The findings from this study support the use of a socio-ecological framework for investigating the development of sedentary behaviour patterns.Copyright © 2012 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.
Ringholm S, Biensø RS, Kiilerich K, Guadalupe-Grau A, Aachmann-Andersen NJ, Saltin B, Plomgaard P, Lundby C, Wojtaszewski JF, Calbet JA, Pilegaard H. Bed rest reduces metabolic protein content and abolishes exercise-induced mRNA responses in human skeletal muscle. Am J Physiol Endocrinol Metab. 2011 Oct;301(4):E649-58. Epub 2011 Jul 12.

The aim was to test the hypothesis that 7 days of bed rest reduces mitochondrial number and expression and activity of oxidative proteins in human skeletal muscle but that exercise-induced intracellular signaling as well as mRNA and microRNA (miR) responses are maintained after bed rest. Twelve young, healthy male subjects completed 7 days of bed rest with vastus lateralis muscle biopsies taken before and after bed rest. In addition, muscle biopsies were obtained from six of the subjects prior to, immediately after, and 3 h after 45 min of one-legged knee extensor exercise performed before and after bed rest. Maximal oxygen uptake decreased by 4%, and exercise endurance decreased nonsignificantly, by 11%, by bed rest. Bed rest reduced skeletal muscle mitochondrial DNA/nuclear DNA content 15%, hexokinase II and sirtuin 1 protein content ?45%, 3-hydroxyacyl-CoA dehydrogenase and citrate synthase activity ?8%, and miR-1 and miR-133a content ?10%. However, cytochrome c and vascular endothelial growth factor (VEGF) protein content as well as capillarization did not change significantly with bed rest. Acute exercise increased AMP-activated protein kinase phosphorylation, peroxisome proliferator activated receptor-? coactivator-1?, and VEGF mRNA content in skeletal muscle before bed rest, but the responses were abolished after bed rest. The present findings indicate that only 7 days of physical inactivity reduces skeletal muscle metabolic capacity as well as abolishes exercise-induced adaptive gene responses, likely reflecting an interference with the ability of skeletal muscle to adapt to exercise.
Rollo, S., Gaston, A., & Prapavessis, H. Cognitive and motivational factors associated with sedentary behavior: A systematic review. Rollo. S., Gaston, A., & Prapavessis, H (2016). Cognitive and motivational factors associated with sedentary behavior: A systematic review. AIMS Public Health, 3(4): 956-984. DOI:10.3934/publichealth.2016.4.956

Excessive time spent in sedentary behavior (SB) is associated with numerous health risks. These associations remain even after controlling for moderate-to-vigorous physical activity (PA) and body mass index, indicating that efforts to promote leisure time physical activity alone are insufficient. Cognitive and motivation variables represent potentially modifiable factors and have the potential of furthering our understanding of sedentary behavior. Hence, a systematic review was conducted to synthesize and critique the literature on the relationship between cognitive and motivational factors and sedentary behaviors. In April 2016, four electronic databases (Psych info, Pub Med, SPORTDiscus, Web of Science) were searched and a total of 4866 titles and abstracts were reviewed. After meeting inclusion criteria, study characteristics were extracted and the methodological quality of each study was assessed according to the Downs and Black Checklist. PRISMA guidelines for reporting of systematic reviews were followed. Twenty-five studies (16 cross-sectional, 8 longitudinal and one examining two populations and employing both a cross-sectional and prospective design) assessed 23 different cognitive and motivational factors. Seventeen studies were theory-based and 8 did not employ a theoretical model. Results showed that among SB-related cognitions, risk factors for greater sedentary time included having a more positive attitude towards SB, perceiving greater social support/norms for SB, reporting greater SB habits, having greater intentions to be sedentary, and having higher intrinsic, introjected, and external motivation towards SB. Protective factors associated with lower sedentary time included having greater feelings of self-efficacy/control over SB and greater intentions to reduce SB. Among PA-related cognitions, protective factors for lower SB included a more positive attitude towards PA, having greater social support/norms for PA, greater self-efficacy/control for PA, higher PA intentions, and higher intrinsic and identified motivation towards PA. In addition, feeling more supported and empowered in general was related with lower levels of SB. The average methodological quality score for included studies was 69% (SD = 9.15%; range 35–80%). In conclusion, a number of cognitive and motivational factors were identified that were associated with sedentarism. These findings have come from reasonably high quality studies. To further extend our understanding of the relation between cognitive and motivational factors and SB, more longitudinal, theory-driven studies examining cognitions and motivation from a sedentary perspective are required. Keywords: sedentary behavior; psychological determinants; cognitive factors; motivational factors
Salmon J, Arundell L, Hume C, Brown H, Hesketh K, Dunstan DW, Daly RM, Pearson N, Cerin E, Moodie M, Sheppard L, Ball K, Bagley S, Chinapaw M, Crawford D. A cluster-randomized controlled trial to reduce sedentary behavior and promote physical activity and health of 8-9 year olds: The Transform-Us! Study. BMC Public Health. 2011 Oct 4;11(1):759. [Epub ahead of print]

ABSTRACT: BACKGROUND: Physical activity (PA) is associated with positive cardio-metabolic health and emerging evidence suggests sedentary behavior (SB) may be detrimental to children’s health independent of PA. The primary aim of the Transform-Us! study is to determine whether an 18-month, behavioral and environmental intervention in the school and family settings results in higher levels of PA and lower rates of SB among 8-9 year old children compared with usual practice (post-intervention and 12-months follow-up). The secondary aims are to determine the independent and combined effects of PA and SB on children’s cardio-metabolic health risk factors; identify the factors that mediate the success of the intervention; and determine whether the intervention is cost-effective. Methods/design: A four-arm cluster-randomized controlled trial (RCT) with a 2×2 factorial design, with schools as the unit of randomization. Twenty schools will be allocated to one of four intervention groups, sedentary behavior (SB-I), physical activity (PA-I), combined SB and PA (SB+PA-I) or current practice control (C), which will be evaluated among approximately 600 children aged 8-9 years in school year 3 living in Melbourne, Australia. All children in year 3 at intervention schools in 2010 (8-9 years) will receive the intervention over an 18-month period with a maintenance ‘booster’ delivered in 2012 and children at all schools will be invited to participate in the evaluation assessments. To maximize the sample and to capture new students arriving at intervention and control schools, recruitment will be on-going up to the post-intervention time point. Primary outcomes are time spent sitting and in PA assessed via accelerometers and inclinometers and survey. DISCUSSION: To our knowledge, Transform-Us! is the first group RCT to examine the effectiveness of intervention strategies for reducing children’s overall sedentary time, promoting PA and optimizing health outcomes. The integration of consistent strategies and messages to children from teachers and parents in both school and family settings is a critical component of this study, and if shown to be effective, may have a significant impact on educational policies as well as on pedagogical and parenting practices. Trial registration: ACTRN12609000715279; Current Controlled Trials ISRCTN83725066.
Salvadego D, Lazzer S, Marzorati M, Porcelli S, Rejc E, Simunic B, Pisot R, di Prampero PE, Grassi B. Functional impairment of skeletal muscle oxidative metabolism during knee-extension exercise after bed rest. J Appl Physiol. 2011 Sep 15. [Epub ahead of print]

A functional evaluation of skeletal muscle oxidative metabolism during dynamic knee-extension (KE) incremental exercises was carried out following a 35-day bed rest (BR) (Valdoltra 2008 BR campaign). Nine young male volunteers (age: 23.5 ± 2.2 years [mean ± SD]) were evaluated. Pulmonary gas exchange, heart rate (HR) and cardiac output (Q, by impedance cardiography), skeletal muscle (vastus lateralis) fractional O(2) extraction and brain (frontal cortex) oxygenation (by near-infrared spectroscopy) were determined during incremental KE. Values at exhaustion were considered “peak”. Peak HR (147 ± 18 beats(.)min(-1) before vs. 146 ± 17 after BR) and peak (17.8 ± 3.3 L(.)min(-1) before vs. 16.1 ± 1.8 after BR) were unaffected by BR. As expected, brain oxygenation did not decrease during KE. Peak O(2) uptake (VO (2)peak) was lower after vs. before BR, both when expressed as L(.)min(-1) (0.99 ± 0.17 vs. 1.26 ± 0.27) and when normalized per unit of quadriceps muscle mass (46.5 ± 6.4 mL(.)min(-1)(.)100g(-1) vs. 56.9 ± 11.0). Skeletal muscle peak fractional O(2) extraction, expressed as a percentage of the maximal values obtained during a transient limb ischemia, was lower after (46.3 ± 12.1%) vs. before BR (66.5 ± 11.2). After eliminating, by the adopted exercise protocol, constraints related to cardiovascular O(2) delivery, a decrease in VO (2)peak and muscle peak capacity of fractional O(2) extraction was found after 35 days of BR. These findings suggest a substantial impairment of oxidative function at the muscle level, “downstream” with respect to bulk blood flow to the exercising muscles, that is possibly at the level of blood flow distribution/O(2) utilization inside the muscle, peripheral O(2) diffusion, intracellular oxidative metabolism.
Saunders TJ, Chaput JP. Is obesity prevention as simple as turning off the television and having a nap? Br J Nutr. 2012 Jun 14:1-2. [Epub ahead of print]

[No abstract available.]
Saunders TJ, Prince SA, Tremblay MS. Clustering of children's activity behaviour: the use of self-report versus direct measures. Int J Behav Nutr Phys Act. 2011 May 25;8:48.

ABSTRACT: While we concur with the objectives of the recent International Journal of Behavioural Nutrition and Physical Activity paper published by Jago and colleagues titled “Physical activity and sedentary behaviour typologies of 10-11 year olds”, we feel that the results as currently presented do not support their conclusions. Though the authors created groups of children with dramatically different patterns of self-reported physical activity and sedentary behaviour, an inspection of the objectively measured accelerometry data shows little difference between the groups. Further, in at least one instance the difference between groups was of the opposite direction when using objective measures, as opposed to the self-report measures used in the published analysis. Thus, we caution the authors from making conclusions based on their self-report data, and propose that they re-analyze their data using their objectively measured data instead.
Schmidt ME, Haines J, O'Brien A, McDonald J, Price S, Sherry B, Taveras EM. Systematic review of effective strategies for reducing screen time among young children. Obesity (Silver Spring). 2012 Jul;20(7):1338-54. doi: 10.1038/oby.2011.348. Epub 2012 Jan 5.

Screen-media use among young children is highly prevalent, disproportionately high among children from lower-income families and racial/ethnic minorities, and may have adverse effects on obesity risk. Few systematic reviews have examined early intervention strategies to limit TV or total screen time; none have examined strategies to discourage parents from putting TVs in their children’s bedrooms or remove TVs if they are already there. In order to identify strategies to reduce TV viewing or total screen time among children <12 years of age, we conducted a systematic review of seven electronic databases to June 2011, using the terms “intervention” and “television,” “media,” or “screen time.” Peer-reviewed intervention studies that reported frequencies of TV viewing or screen-media use in children under age 12 were eligible for inclusion. We identified 144 studies; 47 met our inclusion criteria. Twenty-nine achieved significant reductions in TV viewing or screen-media use. Studies utilizing electronic TV monitoring devices, contingent feedback systems, and clinic-based counseling were most effective. While studies have reduced screen-media use in children, there are several research gaps, including a relative paucity of studies targeting young children (n = 13) or minorities (n = 14), limited long-term (>6 month) follow-up data (n = 5), and few (n = 4) targeting removing TVs from children’s bedrooms. Attention to these issues may help increase the effectiveness of existing strategies for screen time reduction and extend them to different populations.
Semanik PA1, Lee J, Song J, Chang RW, Sohn MW, Ehrlich-Jones LS, Ainsworth BE, Nevitt MM, Kwoh CK, Dunlop DD. Accelerometer-monitored sedentary behavior and observed physical function loss. Am J Public Health. 2015 Mar;105(3):560-6. doi: 10.2105/AJPH.2014.302270. Epub 2015 Jan 20.

OBJECTIVES: We examined whether objectively measured sedentary behavior is related to subsequent functional loss among community-dwelling adults with or at high risk for knee osteoarthritis.METHODS: We analyzed longitudinal data (2008-2012) from 1659 Osteoarthritis Initiative participants aged 49 to 83 years in 4 cities. Baseline sedentary time was assessed by accelerometer monitoring. Functional loss (gait speed and chair stand testing) was regressed on baseline sedentary time and covariates (baseline function; socioeconomics [age, gender, race/ethnicity, income, education], health factors [obesity, depression, comorbidities, knee symptoms, knee osteoarthritis severity, prior knee injury, other lower extremity pain, smoking], and moderate-to-vigorous activity).RESULTS: This cohort spent almost two thirds of their waking hours (average=9.8 h) in sedentary behaviors. Sedentary time was significantly positively associated with subsequent functional loss in both gait speed (-1.66 ft/min decrease per 10% increment sedentary percentage waking hours) and chair stand rate (-0.75 repetitions/min decrease), controlling for covariates.CONCLUSIONS: Being less sedentary was related to less future decline in function, independent of time spent in moderate-to-vigorous activity. Both limiting sedentary activities and promoting physical activity in adults with knee osteoarthritis may be important in maintaining function.
Smith, S., & Prapavessis, H Standing up for students: Effects on classroom performance Smith, S., & Prapavessis, H (2017). Standing up for students: Effects on classroom performance. International Journal of Ergonomics, 7(1), 1-6.

It is known that there are many health risks associated with prolonged sedentary time, but breaking up periods of sitting can reduce these risks (Healy, 2008). University students experience excessive sedentary time during class. Hence, the purpose of this study was to determine the effect of sitting, dynamic sitting, and standing desks on classroom performance of university students. Based on a randomization sequence, 40 participants (N = 20, females, Mage = 20.9) performed three classroom simulations using a classic, dynamic sitting, and standing desk. Each simulation included a typing and memory task. Participants were asked to type the paragraph displayed as fast and as accurate as possible while paying attention to a video. Following the video participants answered multiple-choice questions to assess memory. Results showed no significant differences in speed-accuracy or memory (all p values > .05, ?2 effect size range 0.001-0.027) between sitting, dynamic sitting, and standing desks.
Smith, S., & Prapavessis, H. Standing up for students: Effects on classroom performance. Smith, S., & Prapavessis, H (2017). Standing up for students: Effects on classroom performance. International Journal of Ergonomics, 7(1), 1-6.

[No abstract available.]
Sohn MW1, Manheim LM2, Chang RW3, Greenland P4, Hochberg MC5, Nevitt MC6, Semanik PA7, Dunlop DD8. Sedentary behavior and blood pressure control among osteoarthritis initiative participants. Osteoarthritis Cartilage. 2014 Sep;22(9):1234-40. doi: 10.1016/j.joca.2014.07.007. Epub 2014 Jul 18.

OBJECTIVE: To examine the association between sedentary behavior and blood pressure (BP) among Osteoarthritis Initiative (OAI) participants.DESIGN: We conducted a cross-sectional analysis of the OAI 48-month visit participants whose physical activity was measured using accelerometers. Participants were classified into four quartiles according to the percentage of wear time that was sedentary (<100 activity counts per min). Users of antihypertensive medications or non-steroidal anti-inflammatory drugs (NSAIDs) were excluded. Our main outcomes were systolic and diastolic blood pressures (SBP and DBP) and “elevated BP” defined as BP ? 130/85 mm Hg.RESULTS: For this study cohort (N = 707), mean BP was 121.4 ± 15.6/74.7 ± 9.5 mm Hg and 33% had elevated BP. SBP had a graded association with increased sedentary time (P for trend = 0.02). The most sedentary quartile had 4.26 mm Hg higher SBP (95% confidence interval (CI), 0.69-7.82; P = 0.02) than the least sedentary quartile, adjusting for age, moderate-to-vigorous (MV) physical activity, and other demographic and health factors. The probability of having elevated BP significantly increased in higher sedentary quartiles (P for trend = 0.046). There were no significant findings for DBP.CONCLUSION: A strong graded association was demonstrated between sedentary behavior and increased SBP and elevated BP, independent of time spent in MV physical activity. Reducing daily sedentary time may lead to improvement in BP and reduction in cardiovascular risk.Published by Elsevier Ltd.KEYWORDS: Blood pressure; Osteoarthritis; Physical activity; Sedentary lifestyle
Song J1, Lindquist LA, Chang RW, Semanik PA, Ehrlich-Jones LS, Lee J, Sohn MW, Dunlop DD. Sedentary Behavior as a Risk Factor for Physical Frailty Independent of Moderate Activity: Results From the Osteoarthritis Initiative. Am J Public Health. 2015 Jul;105(7):1439-45. doi: 10.2105/AJPH.2014.302540. Epub 2015 May 14.

OBJECTIVES: This prospective longitudinal study investigated the association between baseline objectively measured sedentary time and 2-year onset of physical frailty.METHODS: We studied 1333 Osteoarthritis Initiative participants 55 to 83 years of age who were at risk for physical frailty, as assessed via low gait speed (
Stamatakis E, Hamer M, Dunstan DW. Screen-based entertainment time, all-cause mortality, and cardiovascular events: population-based study with ongoing mortality and hospital events follow-up. J Am Coll Cardiol. 2011 Jan 18;57(3):292-9.

OBJECTIVES: The aim of this study was to examine the independent relationships of television viewing or other screen-based entertainment (“screen time”) with all-cause mortality and clinically confirmed cardiovascular disease (CVD) events. A secondary objective was to examine the extent to which metabolic (body mass index, high-density lipoprotein and total cholesterol) and inflammatory (C-reactive protein) markers mediate the relationship between screen time and CVD events.BACKGROUND: Although some evidence suggests that prolonged sitting is linked to CVD risk factor development regardless of physical activity participation, studies with hard outcomes are scarce.METHODS: A population sample of 4,512 (1,945 men) Scottish Health Survey 2003 respondents (?35 years) were followed up to 2007 for all-cause mortality and CVD events (fatal and nonfatal combined). Main exposures were interviewer-assessed screen time (<2 h/day; 2 to <4 h/day; and ?4 h/day) and moderate to vigorous intensity physical activity.RESULTS: Two hundred fifteen CVD events and 325 any-cause deaths occurred during 19,364 follow-up person-years. The covariable (age, sex, ethnicity, obesity, smoking, social class, long-standing illness, marital status, diabetes, hypertension)-adjusted hazard ratio (HR) for all-cause mortality was 1.52 (95% confidence interval [CI]: 1.06 to 2.16) and for CVD events was 2.30 (95% CI: 1.33 to 3.96) for participants engaging in ?4 h/day of screen time relative to <2 h/day. Adjusting for physical activity attenuated these associations only slightly (all-cause mortality: HR: 1.48, 95% CI: 1.04 to 2.13; CVD events: HR: 2.25, 95% CI: 1.30 to 3.89). Exclusion of participants with CVD events in the first 2 years of follow-up and previous cancer registrations did not change these results appreciably. Approximately 25% of the association between screen time and CVD events was explained collectively by C-reactive protein, body mass index, and high-density lipoprotein cholesterol.CONCLUSIONS: Recreational sitting, as reflected by television/screen viewing time, is related to raised mortality and CVD risk regardless of physical activity participation. Inflammatory and metabolic risk factors partly explain this relationship.Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Stamatakis E, Hirani V, Rennie K. Moderate-to-vigorous physical activity and sedentary behaviours in relation to body mass index-defined and waist circumference-defined obesity. Br J Nutr. 2009 Mar;101(5):765-73. Epub 2008 Aug 5.

The aim of the present study was to investigate the relationships of physical activity types and sedentary behaviour with BMI and waist circumference (WC). The sample comprised 6215 adults (2775 men, 3440 women) aged 16 years and over living in Scotland. Self-reported physical activity of moderate to vigorous intensity (MVIA) included domestic activity, walking, and sports and exercises. MVIA levels were classified as being inactive, being insufficiently active, being sufficiently active for general health benefits and being sufficiently active for obesity prevention. Sedentary time was defined as television and other screen-based entertainment time (TVSE). Dependent variables were BMI-defined obesity (BMI-OB) and WC-defined obesity (WC-OB). TVSE was positively related to both WC-OB (adjusted OR 1.69 (95 % CI 1.39, 2.05) for > or = 4 h of TVSE per d compared with < 2 h/d) and BMI-OB (OR 1.88; 95 % CI 1.51, 2.35) independently of MVIA. Those classified as most active who reported > or = 4 h/d of TVSE had higher prevalence of BMI-OB (18.9 v. 8.3 %; P < 0.05) and WC-OB (28.0 v. 10.0 %; P < 0.01) than those equally active with < 2 h/d of TVSE. Sports and walking were related inversely to WC-OB (OR for no time compared with > or = 30 min/d: 1.55 (95 % CI 1.24, 1.94); 2.06 (95 % CI 1.64, 2.58)), but only walking was related to BMI-OB (OR 1.94; 95 % CI 1.58, 2.37). Domestic physical activity was not related to BMI-OB or WC-OB. In conclusion, physical activity and sedentary behaviour are independently related to obesity. Public health recommendations should both promote physical activity and discourage engagement in sedentary pursuits.
Stephens BR, Granados K, Zderic TW, Hamilton MT, Braun B. Effects of 1 day of inactivity on insulin action in healthy men and women: interaction with energy intake. Metabolism. 2011 Jul;60(7):941-9. Epub 2010 Nov 10.

Prolonged periods of limited muscle activity can reduce insulin action. Acute changes in low muscle activity (ie, sitting) have not been assessed. In addition, unless energy intake is reduced during sitting to match low expenditure, the concurrent energy surplus may explain lower insulin action. The objective of the study was to evaluate the acute effect of sitting, with and without energy surplus, on insulin action. Fourteen young (26.1 ± 4.5 years, mean ± SD), nonobese (23.7% ± 7.1% fat), fit (peak oxygen consumption = 49.1 ± 3.3 mL·kg(-1)·min(-1)) men (n = 7) and women (n = 7) completed three 24-hour conditions: (1) an active, no-sitting condition (high energy expenditure of 2944 ± 124 kcal with energy intake matched to expenditure) = NO-SIT; (2) low energy expenditure (sitting) of 2195 ± 121 kcal with no reduction in energy intake (energy surplus) = SIT; and (3) sitting with energy intake reduced to 2139 ± 118 kcal to match low expenditure (energy balance) = SIT-BAL. Insulin action was measured the following morning during a continuous infusion of [6,6-(2)H]-glucose. Data were analyzed using linear mixed-effects models with planned contrasts. Compared with NO-SIT, insulin action, defined as whole-body rate of glucose disappearance normalized to mean plasma insulin, was reduced by 39% in SIT (P < .001) and by 18% in SIT-BAL (P = .07). Insulin action was higher in SIT-BAL compared with SIT (P = .04). One day of sitting considerably reduced insulin action; this effect was minimized, but not prevented, when energy intake was reduced to match expenditure. Strategies to limit daily sitting may reduce metabolic disease risk.Copyright © 2011 Elsevier Inc. All rights reserved.
Straker L, Abbott RA, Heiden M, Mathiassen SE, Toomingas A. Sit-stand desks in call centres: Associations of use and ergonomics awareness with sedentary behavior. Appl Ergon. 2013 Jul;44(4):517-22. doi: 10.1016/j.apergo.2012.11.001. Epub 2012 Dec 4.

OBJECTIVE: To investigate whether or not use of sit-stand desks and awareness of the importance of postural variation and breaks are associated with the pattern of sedentary behavior in office workers.METHOD: The data came from a cross-sectional observation study of Swedish call centre workers. Inclinometers recorded ‘seated’ or ‘standing/walking’ episodes of 131 operators over a full work shift. Differences in sedentary behavior based on desk type and awareness of the importance of posture variation and breaks were assessed by non-parametric analyses.RESULTS: 90 (68.7%) operators worked at a sit-stand desk. Working at a sit-stand desk, as opposed to a sit desk, was associated with less time seated (78.5 vs 83.8%, p = 0.010), and less time taken to accumulate 5 min of standing/walking (36.2 vs 46.3 min, p = 0.022), but no significant difference to sitting episode length or the number of switches between sitting and standing/walking per hour. Ergonomics awareness was not associated with any sedentary pattern variable among those using a sit-stand desk.CONCLUSION: Use of sit-stand desks was associated with better sedentary behavior in call centre workers, however ergonomics awareness did not enhance the effect.Copyright © 2012 Elsevier Ltd and The Ergonomics Society. All rights reserved.
Teatske M Altenburg, Amika S Singh, Willem van Mechelen, Johannes Brug and Mai JM Chinapaw Direction of the association between body fatness and self-reported screen time in Dutch adolescents International Journal of Behavioral Nutrition and Physical Activity 2012, 9:4 doi:10.1186/1479-5868-9-4

Background Screen time has been associated with pediatric overweight. However, it is unclear whether overweight predicts or is predicted by excessive amounts of screen time. The aim of this study was to examine the direction of the association between screen time and body fatness in Dutch adolescents. Methods Longitudinal data of 465 Dutch adolescents (mean age at baseline 13 years, 53% boys) was used. Body fatness (objectively measured BMI, four skin folds and waist- and hip circumference), self-reported time spent watching TV and computer use, and aerobic fitness (shuttle run test) were assessed in all participants at three time points during 12 months. Multi-level linear autoregressive analysis was used to examine whether screen time predicted body fatness in the following time period and whether body fatness predicted screen time. Analyses were performed for boys and girls separately and adjusted for ethnicity and aerobic fitness. Results Time spent TV viewing did predict changes in BMI and hip circumference in boys, but not in girls, in the subsequent period. Computer time significantly predicted increases in skinfolds in boys and girls and increases in BMI in girls. Body fatness did not predict any changes in screen time. Conclusion The present study only partly supports the widely posited hypothesis that higher levels of screen time cause increases in body fatness. In addition, this study demonstrates that high levels of body fatness do not predict increases in screen time.
Theou O, Jakobi JM, Vandervoort AA, Jones GR. A comparison of physical activity (PA) assessment tools across levels of frailty. Arch Gerontol Geriatr. 2011 Dec 30. [Epub ahead of print]

PURPOSE: Determine which PA assessment tools are most closely related to frailty and whether PA is different across levels of frailty.METHODS: Fifty community-dwelling Greek older women (63-90years) participated in this study. PA was measured objectively over 10h using an accelerometer, a heart rate (HR) monitor, a portable electromyography (EMG) unit, and a global positioning system (GPS) and subjectively using the short version of the Minnesota Leisure Time Activity Questionnaire (MLTAQ). Participants were divided into three tertiles based on level of frailty as calculated from a Frailty Index (FI): low FI group (<0.17 FI); intermediate FI group (0.17-0.38 FI); and high FI group (>0.38 FI).RESULTS: Accelerometer step counts had the strongest correlation with frailty and were different across levels of frailty. The percentage of time engaged in PA was 31±15% when PA was determined using an accelerometer. Forty-five percent of the variability in the FI was explained by a combination of PA assessment tools including; accelerometer, EMG, GPS, and MLTAQ. The individual contribution of EMG determined activity from the biceps brachii (BB) to the FI prediction was 16%. Accelerometer contributed an additional 10% and time engaged in PA, as assessed with the MLTAQ, added an additional 6% to the prediction of FI score.CONCLUSIONS: PA assessment tools, when used in combination, provide important information about the PA accumulation of older women across levels of frailty.Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Thorp AA, Owen N, Neuhaus M, Dunstan DW. Sedentary behaviors and subsequent health outcomes in adults a systematic review of longitudinal studies, 1996-2011. Am J Prev Med. 2011 Aug;41(2):207-15.

CONTEXT: To systematically review and provide an informative synthesis of findings from longitudinal studies published since 1996 reporting on relationships between self-reported sedentary behavior and device-based measures of sedentary time with health-related outcomes in adults.EVIDENCE ACQUISITION: Studies published between 1996 and January 2011 were identified by examining existing literature reviews and by systematic searches in Web of Science, MEDLINE, PubMed, and PsycINFO. English-written articles were selected according to study design, targeted behavior, and health outcome.EVIDENCE SYNTHESIS: Forty-eight articles met the inclusion criteria; of these, 46 incorporated self-reported measures including total sitting time; TV viewing time only; TV viewing time and other screen-time behaviors; and TV viewing time plus other sedentary behaviors. Findings indicate a consistent relationship of self-reported sedentary behavior with mortality and with weight gain from childhood to the adult years. However, findings were mixed for associations with disease incidence, weight gain during adulthood, and cardiometabolic risk. Of the three studies that used device-based measures of sedentary time, one showed that markers of obesity predicted sedentary time, whereas inconclusive findings have been observed for markers of insulin resistance.CONCLUSIONS: There is a growing body of evidence that sedentary behavior may be a distinct risk factor, independent of physical activity, for multiple adverse health outcomes in adults. Prospective studies using device-based measures are required to provide a clearer understanding of the impact of sedentary time on health outcomes.Copyright © 2011 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.
Thyfault JP, Krogh-Madsen R. Metabolic disruptions induced by reduced ambulatory activity in free living humans. J Appl Physiol. 2011 Jun 2. [Epub ahead of print]

Physical inactivity likely plays a role in the development of insulin resistance and obesity, however, direct evidence is minimal and mechanisms of action remain unknown. Studying metabolic outcomes that occur after transitioning from higher to lower levels of physical activity is the best tool to answer these questions. Previous studies have successfully used more extreme models of inactivity including bedrest, or the cessation of exercise in highly trained endurance athlete to provide novel findings. However, these models do not accurately reflect the type of inactivity experienced by a large majority of the population. Recent studies have used a more applicable model in which active (~10,000 steps/day), healthy young controls are asked to transition to an inactive lifestyle (~1,500 steps/day) for a 14 day period. The transition to inactivity resulted in reduced insulin sensitivity and increased central adiposity. This review will discuss the outcomes of these studies, their implications for the cause/effect relationship between central adiposity and insulin resistance, and provide rationale for why inactivity induces these factors. In addition, the experimental challenges of directly linking acute responses to inactivity to chronic disease will also be discussed.
Tremblay MS, Colley RC, Saunders TJ, Healy GN, Owen N. Physiological and health implications of a sedentary lifestyle. Appl Physiol Nutr Metab. 2010 Dec;35(6):725-40.

Sedentary behaviour is associated with deleterious health outcomes, which differ from those that can be attributed to a lack of moderate to vigorous physical activity. This has led to the field of “sedentary physiology”, which may be considered as separate and distinct from exercise physiology. This paper gives an overview of this emerging area of research and highlights the ways that it differs from traditional exercise physiology. Definitions of key terms associated with the field of sedentary physiology and a review of the self-report and objective methods for assessing sedentary behaviour are provided. Proposed mechanisms of sedentary physiology are examined, and how they differ from those linking physical activity and health are highlighted. Evidence relating to associations of sedentary behaviours with major health outcomes and the population prevalence and correlates of sedentary behaviours are reviewed. Recommendations for future research are proposed.
Tremblay MS, Leblanc AG, Carson V, Choquette L, Connor Gorber S, Dillman C, Duggan M, Gordon MJ, Hicks A, Janssen I, Kho ME, Latimer-Cheung AE, Leblanc C, Murumets K, Okely AD, Reilly JJ, Stearns JA, Timmons BW, Spence JC. Canadian Sedentary Behaviour Guidelines for the Early Years (aged 0-4 years). Appl Physiol Nutr Metab. 2012 Apr;37(2):370-80. Epub 2012 Mar 27.

The Canadian Society for Exercise Physiology (CSEP), with assistance from multiple partners, stakeholders, and researchers, developed the first Canadian Sedentary Behaviour Guidelines for the Early Years (aged 0-4 years). These national guidelines are in response to a call from health and health care professionals, child care providers, and fitness practitioners for guidance on sedentary behaviour in the early years. The guideline development process followed the Appraisal of Guidelines for Research Evaluation (AGREE) II framework. The recommendations are informed by evidence from a systematic review that examined the relationships between sedentary behaviour (predominantly screen time) and health indicators (healthy body weight, bone and skeletal health, motor skill development, psychosocial health, cognitive development, and cardio-metabolic disease risk factors) for three age groups (infants aged <1 year; toddlers aged 1-2 years; preschoolers aged 3-4 years). Evidence from the review was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. The new guidelines include a preamble to provide context, followed by the specific recommendations. The final guidelines benefitted from extensive on-line consultations with input from >900 domestic and international stakeholders, end-users, and key informants. The final guidelines state: for healthy growth and development, caregivers should minimize the time infants (aged <1 year), toddlers (aged 1-2 years), and preschoolers (aged 3-4 years) spend being sedentary during waking hours. This includes prolonged sitting or being restrained (e.g., stroller, high chair) for more than 1 h at a time. For those under 2 years, screen time (e.g., TV, computer, electronic games) is not recommended. For children 2-4 years, screen time should be limited to under 1 h per day; less is better.
Tremblay MS, Leblanc AG, Janssen I, Kho ME, Hicks A, Murumets K, Colley RC, Duggan M. Canadian sedentary behaviour guidelines for children and youth. Appl Physiol Nutr Metab. 2011 Feb;36(1):59-64; 65-71.

The Canadian Society for Exercise Physiology (CSEP), in partnership with the Healthy Active Living and Obesity Research Group (HALO) at the Children’s Hospital of Eastern Ontario Research Institute, and in collaboration with ParticipACTION, and others, has developed the Canadian Sedentary Behaviour Guidelines for Children (aged 5-11 years) and Youth (aged 12-17 years). The guidelines include a preamble to provide context, followed by the specific recommendations for sedentary behaviour. The entire development process was guided by the Appraisal of Guidelines for Research Evaluation (AGREE) II instrument, which is the international standard for clinical practice guideline development. Thus, the guidelines have gone through a rigorous and transparent developmental process and the recommendations are based on evidence from a systematic review and interpretation of the research evidence. The final guidelines benefitted from an extensive online consultation process with 230 domestic and international stakeholders and key informants. The final guideline recommendations state that for health benefits, children (aged 5-11 years) and youth (aged 12-17 years) should minimize the time that they spend being sedentary each day. This may be achieved by (i) limiting recreational screen time to no more than 2 h per day - lower levels are associated with additional health benefits; and (ii) limiting sedentary (motorized) transport, extended sitting time, and time spent indoors throughout the day. These are the first evidence-based Canadian Sedentary Behaviour Guidelines for Children and Youth and provide important and timely recommendations for the advancement of public health based on a systematic synthesis, interpretation, and application of the current scientific evidence.
Tremblay MS, Leblanc AG, Kho ME, Saunders TJ, Larouche R, Colley RC, Goldfield G, Gorber SC. Systematic review of sedentary behaviour and health indicators in school-aged children and youth. Int J Behav Nutr Phys Act. 2011 Sep 21;8:98.

ABSTRACT: Accumulating evidence suggests that, independent of physical activity levels, sedentary behaviours are associated with increased risk of cardio-metabolic disease, all-cause mortality, and a variety of physiological and psychological problems. Therefore, the purpose of this systematic review is to determine the relationship between sedentary behaviour and health indicators in school-aged children and youth aged 5-17 years. Online databases (MEDLINE, EMBASE and PsycINFO), personal libraries and government documents were searched for relevant studies examining time spent engaging in sedentary behaviours and six specific health indicators (body composition, fitness, metabolic syndrome and cardiovascular disease, self-esteem, pro-social behaviour and academic achievement). 232 studies including 983,840 participants met inclusion criteria and were included in the review. Television (TV) watching was the most common measure of sedentary behaviour and body composition was the most common outcome measure. Qualitative analysis of all studies revealed a dose-response relation between increased sedentary behaviour and unfavourable health outcomes. Watching TV for more than 2 hours per day was associated with unfavourable body composition, decreased fitness, lowered scores for self-esteem and pro-social behaviour and decreased academic achievement. Meta-analysis was completed for randomized controlled studies that aimed to reduce sedentary time and reported change in body mass index (BMI) as their primary outcome. In this regard, a meta-analysis revealed an overall significant effect of -0.81 (95% CI of -1.44 to -0.17, p = 0.01) indicating an overall decrease in mean BMI associated with the interventions. There is a large body of evidence from all study designs which suggests that decreasing any type of sedentary time is associated with lower health risk in youth aged 5-17 years. In particular, the evidence suggests that daily TV viewing in excess of 2 hours is associated with reduced physical and psychosocial health, and that lowering sedentary time leads to reductions in BMI.
Treuth MS, Baggett CD, Pratt CA, Going SB, Elder JP, Charneco EY, Webber LS. A longitudinal study of sedentary behavior and overweight in adolescent girls. Obesity (Silver Spring). 2009 May;17(5):1003-8. Epub 2009 Jan 22.

The aim of this study is to examine sedentary and light activity in relation to overweight in adolescent girls. Adolescent girls were randomly recruited from 36 schools participating in the Trial of Activity for Adolescent Girls (TAAG). Assessments included age, ethnicity, socioeconomic status, and body composition estimated from weight, height, and triceps skinfold. Sedentary and light activity was measured for 6 days using accelerometry in 6th and in 8th grade among two randomly sampled cross-sections of girls. Sedentary activity increased from the 6th to 8th grade by 51.5 min/day. In the 8th grade, a significantly higher number of hours in sedentary activity for each of the 6-days of measurement were evident with higher tertiles of percent body fat (30-35%, >35% fat) (P < 0.05), but not across all increasing tertiles of BMI (5th to 85th, 85th to 95th, and >95th percentiles). The increase in sedentary activity was observed on weekdays, but not on weekends for percent body fat tertiles. In the cohort of girls measured in both 6th and 8th grades, the mean cross-sectional coefficient estimates were significant for percent body fat, but not BMI for sedentary and light activities. Adolescent girls from the 6th to 8th grade are shifting their time from light to more sedentary activity as measured by accelerometers. In addition, the increase in sedentary activity is not associated with an adverse effect on BMI or percent body fat. The eventual impact of this shift to a more sedentary lifestyle on body composition and other outcomes needs to be evaluated further.
Trost SG, Loprinzi PD, Moore R, Pfeiffer KA. Comparison of Accelerometer Cut Points for Predicting Activity Intensity in Youth. Med. Sci. Sports Exerc. 2011;43:1360.

The absence of comparative validity studies has prevented researchers from reaching consensus regarding the application of intensity-related accelerometer cut points for children and adolescents. Purpose: This study aimed to evaluate the classification accuracy of five sets of independently developed ActiGraph cut points using energy expenditure, measured by indirect calorimetry, as a criterion reference standard. Methods: A total of 206 participants between the ages of 5 and 15 yr completed 12 standardized activity trials. Trials consisted of sedentary activities (lying down, writing, computer game), lifestyle activities (sweeping, laundry, throw and catch, aerobics, basketball), and ambulatory activities (comfortable walk, brisk walk, brisk treadmill walk, running). During each trial, participants wore an ActiGraph GT1M, and V?O2 was measured breath-by-breath using the Oxycon Mobile portable metabolic system. Physical activity intensity was estimated using five independently developed cut points: Freedson/Trost (FT), Puyau (PU), Treuth (TR), Mattocks (MT), and Evenson (EV). Classification accuracy was evaluated via weighted ? statistics and area under the receiver operating characteristic curve (ROC-AUC). Results: Across all four intensity levels, the EV (? = 0.68) and FT (? = 0.66) cut points exhibited significantly better agreement than TR (? = 0.62), MT (? = 0.54), and PU (? = 0.36). The EV and FT cut points exhibited significantly better classification accuracy for moderate- to vigorous-intensity physical activity (ROC-AUC = 0.90) than TR, PU, or MT cut points (ROC-AUC = 0.77-0.85). Only the EV cut points provided acceptable classification accuracy for all four levels of physical activity intensity and performed well among children of all ages. The widely applied sedentary cut point of 100 counts per minute exhibited excellent classification accuracy (ROC-AUC = 0.90). Conclusions: On the basis of these findings, we recommend that researchers use the EV ActiGraph cut points to estimate time spent in sedentary, light-, moderate-, and vigorous-intensity activity in children and adolescents.
Tudor-Locke C, Brashear MM, Johnson WD, Katzmarzyk PT. Accelerometer profiles of physical activity and inactivity in normal weight, overweight, and obese U.S. men and women. Int J Behav Nutr Phys Act. 2010 Aug 3;7:60.

ABSTRACT:BACKGROUND: The 2005-2006 National Health and Nutrition Examination Survey (NHANES) is used to describe an accelerometer-derived physical activity/inactivity profile in normal weight (BMI < 25 kg/m2), overweight (25 /= 30 kg/m2) U.S. adults.METHODS: We computed physical activity volume indicators (activity counts/day, uncensored and censored steps/day), rate indicators (e.g., steps/minute), time indicators (employing NHANES activity counts/minute cut points to infer time in non-wear, sedentary, low, light, moderate, and vigorous intensities), the number of breaks in sedentary time (occasions when activity counts rose from < 100 activity/counts in one minute to >/= 100 activity counts in the subsequent minute), achievement of public health guidelines, and classification by step-defined physical activity levels. Data were examined for evidence of consistent and significant gradients across BMI-defined categories.RESULTS: In 2005-2006, U.S adults averaged 6,564 +/- SE 107 censored steps/day, and after considering non-wear time, they spent approximately 56.8% of the rest of the waking day in sedentary time, 23.7% in low intensity, 16.7% in light intensity, 2.6% in moderate intensity, and 0.2% in vigorous intensity. Overall, approximately 3.2% of U.S. adults achieved public health guidelines. The normal weight category took 7,190 +/- SE 157 steps/day, and spent 25.7 +/- 0.9 minutes/day in moderate intensity and 7.3 +/- 0.4 minutes/day in vigorous intensity physical activity. The corresponding numbers for the overweight category were 6,879 +/- 140 steps/day, 25.3 +/- 0.9 minutes/day, and 5.3 +/- 0.5 minutes/day and for the obese category 5,784 +/- 124 steps/day, 17.3 +/- 0.7 minutes/day and 3.2 +/- 0.4 minutes/day. Across BMI categories, increasing gradients and significant trends were apparent in males for sedentary time and decreasing gradients and significant trends were evident in time spent in light intensity, moderate intensity, and vigorous intensity. For females, there were only consistent gradients and significant trends apparent for decreasing amounts of time spent in moderate and vigorous intensity.CONCLUSIONS: Simple indicators of physical activity volume (i.e., steps/day) and time in light, moderate or vigorous intensity physical activity differ across BMI categories for both sexes, suggesting that these should continue to be targets for surveillance.
Uijtdewilligen L, Nauta J, Singh AS, van Mechelen W, Twisk JW, van der Horst K, Chinapaw MJ. Determinants of physical activity and sedentary behaviour in young people: a review and quality synthesis of prospective studies. Br J Sports Med. 2011 Sep;45(11):896-905.

OBJECTIVE: The aim of this systematic review was to summarise and update the existing literature on determinants of physical activity and sedentary behaviour in young people, considering the methodological quality of the studies.METHODS: Prospective studies were identified from searches in PubMed and PsycINFO, from April 2004 through November 2010. The authors included studies investigating the association between determinants of overall physical (in)activity and/or sedentary behaviour in healthy children or adolescents. When a determinant was investigated for its association with physical (in)activity and sedentary behaviour assessed between ages of 4-12, or mean age ?12, it was classified as ‘child determinant’. When a determinant was investigated for its association with physical activity and sedentary behaviour assessed between ages of 13-18 or mean age >12, it was classified as ‘adolescent determinant’. Included articles were scored on their methodological quality and a best-evidence synthesis was applied to summarise the results.RESULTS: The authors identified 30 papers, of which seven were of high methodological quality. Intention was found as a determinant of children’s physical activity. Determinants of adolescents’ physical activity were age (ie, older children were more active), ethnicity (ie, being of African–American descent determined being less physically active) and planning. The authors found insufficient evidence for determinants of sedentary behaviour.CONCLUSION: Studies on determinants of physical activity and sedentary behaviour were in general of poor methodological quality. To develop long-term effective interventions that increase physical activity and decrease time spent in sedentary behaviours in young people, we need more high quality prospective evidence on the determinants of these behaviours.
Uijtdewilligen L, Singh AS, Twisk JW, Koppes LLj, van Mechelen W, Chinapaw MJ. Adolescent predictors of objectively measured physical activity and sedentary behaviour at age 42: the Amsterdam Growth and Health Longitudinal Study (AGAHLS). Int J Behav Nutr Phys Act. 2011 Oct 2;8:107.

ABSTRACT:BACKGROUND: This study investigated the associations of physical characteristics and personality in adolescence with physical activity and sedentary behaviour in adulthood.FINDINGS: Physical characteristics (i.e. objectively measured BMI, sum of skin folds, MOPER test battery performance), and personality (i.e. self-reported inadequacy, social inadequacy, rigidity, self-sufficiency/recalcitrance, dominance, achievement motivation, facilitating anxiety, debilitating anxiety, and social desirability) were assessed in 217 adolescent boys (Mean 13.0, SD 0.6) and girls (Mean 12.9, SD 0.6). Twenty-nine years later, at the age of 42, their physical activity and sedentary behaviour were assessed by means of accelerometry. Boys who scored lower on self-sufficiency/recalcitrance and higher on facilitating anxiety spent more time sedentary in adulthood. Girls with a superior standing high jump performance, and a lower score on social desirability spent more time sedentary in adulthood. In contrast with sedentary behaviour, physical activity at age 42 year could not be predicted by physical characteristics or personality in adolescence.CONCLUSIONS: Sedentary behaviour in adulthood was partly explained by physical characteristics and/or personality in adolescence. Thus, our results suggest that it may be possible to identify people who are at risk of becoming sedentary at a rather young age.
Ulf Ekelund; Jian’an Luan; Lauren B. Sherar; Dale W. Esliger; Pippa Griew; Ashley Cooper, for the International Children's Accelerometry Database (ICAD) Collaborators Moderate to Vigorous Physical Activity and Sedentary Time and Cardiometabolic Risk Factors in Children and Adolescents

Context Sparse data exist on the combined associations between physical activity and sedentary time with cardiometabolic risk factors in healthy children. Objective To examine the independent and combined associations between objectively measured time in moderate- to vigorous-intensity physical activity (MVPA) and sedentary time with cardiometabolic risk factors. Design, Setting, and Participants Pooled data from 14 studies between 1998 and 2009 comprising 20 871 children (aged 4-18 years) from the International Children\'s Accelerometry Database. Time spent in MVPA and sedentary time were measured using accelerometry after reanalyzing raw data. The independent associations between time in MVPA and sedentary time, with outcomes, were examined using meta-analysis. Participants were stratified by tertiles of MVPA and sedentary time. Main Outcome Measures Waist circumference, systolic blood pressure, fasting triglycerides, high-density lipoprotein cholesterol, and insulin. Results Times (mean [SD] min/d) accumulated by children in MVPA and being sedentary were 30 (21) and 354 (96), respectively. Time in MVPA was significantly associated with all cardiometabolic outcomes independent of sex, age, monitor wear time, time spent sedentary, and waist circumference (when not the outcome). Sedentary time was not associated with any outcome independent of time in MVPA. In the combined analyses, higher levels of MVPA were associated with better cardiometabolic risk factors across tertiles of sedentary time. The differences in outcomes between higher and lower MVPA were greater with lower sedentary time. Mean differences in waist circumference between the bottom and top tertiles of MVPA were 5.6 cm (95% CI, 4.8-6.4 cm) for high sedentary time and 3.6 cm (95% CI, 2.8-4.3 cm) for low sedentary time. Mean differences in systolic blood pressure for high and low sedentary time were 0.7 mm Hg (95% CI, ?0.07 to 1.6) and 2.5 mm Hg (95% CI, 1.7-3.3), and for high-density lipoprotein cholesterol, differences were ?2.6 mg/dL (95% CI, ?1.4 to ?3.9) and ?4.5 mg/dL (95% CI, ?3.3 to ?5.6), respectively. Geometric mean differences for insulin and triglycerides showed similar variation. Those in the top tertile of MVPA accumulated more than 35 minutes per day in this intensity level compared with fewer than 18 minutes per day for those in the bottom tertile. In prospective analyses (N = 6413 at 2.1 years’ follow-up), MVPA and sedentary time were not associated with waist circumference at follow-up, but a higher waist circumference at baseline was associated with higher amounts of sedentary time at follow-up. Conclusion Higher MVPA time by children and adolescents was associated with better cardiometabolic risk factors regardless of the amount of sedentary time.
Vallance JK, Winkler EA, Gardiner PA, Healy GN, Lynch BM, Owen N. Associations of objectively-assessed physical activity and sedentary time with depression: NHANES (2005-2006). Prev Med. 2011 Oct;53(4-5):284-8. Epub 2011 Jul 23.

BACKGROUND: Studies provide conflicting evidence for the protective effects of moderate-to-vigorous-intensity physical activity on depression. Recent evidence suggests that sedentary behaviors may also be associated with depression.PURPOSE: To examine the associations of accelerometer-derived moderate-to-vigorous-intensity physical activity and sedentary time with depression among a population-based sample.METHODS: Cross-sectional study using 2,862 adults from the 2005-2006 US National Health and Nutrition Examination Survey. ActiGraph accelerometers were used to derive both moderate-to-vigorous-intensity physical activity and sedentary time.RESULTS: Depression occurred in 6.8% of the sample. For moderate-to-vigorous-intensity physical activity, compared with those in quartile 1 (least active), significantly lower odds of depression were observed for those participants in quartiles 2 (OR=0.55, 95% CI, 0.34 to 0.89), 3 (OR=0.49, 95% CI, 0.26 to 0.93), and 4 (most active) (OR=0.37, 95% CI, 0.20 to 0.70) (p for trend p<0.01). In overweight/obese participants only, those in quartile 4 (most sedentary) had significantly higher odds for depression than those in quartile 1 (least sedentary) [quartile 3 vs 1 (OR=1.94, 95% CI, 1.01 to 3.68) and 4 vs 1 (OR=3.09, 95% CI, 1.25 to 7.68)].CONCLUSION: The current study identified lower odds of depression were associated with increasing moderate-to-vigorous-intensity physical activity and decreasing sedentary time, at least within overweight/obese adults.Copyright © 2011 Elsevier Inc. All rights reserved.
van der Ploeg HP, Chey T, Korda RJ, Banks E, Bauman A. Sitting time and all-cause mortality risk in 222 497 Australian adults. Arch Intern Med. 2012 Mar 26;172(6):494-500.

BACKGROUND: Prolonged sitting is considered detrimental to health, but evidence regarding the independent relationship of total sitting time with all-cause mortality is limited. This study aimed to determine the independent relationship of sitting time with all-cause mortality.METHODS: We linked prospective questionnaire data from 222 497 individuals 45 years or older from the 45 and Up Study to mortality data from the New South Wales Registry of Births, Deaths, and Marriages (Australia) from February 1, 2006, through December 31, 2010. Cox proportional hazards models examined all-cause mortality in relation to sitting time, adjusting for potential confounders that included sex, age, education, urban/rural residence, physical activity, body mass index, smoking status, self-rated health, and disability.RESULTS: During 621 695 person-years of follow-up (mean follow-up, 2.8 years), 5405 deaths were registered. All-cause mortality hazard ratios were 1.02 (95% CI, 0.95-1.09), 1.15 (1.06-1.25), and 1.40 (1.27-1.55) for 4 to less than 8, 8 to less than 11, and 11 or more h/d of sitting, respectively, compared with less than 4 h/d, adjusting for physical activity and other confounders. The population-attributable fraction for sitting was 6.9%. The association between sitting and all-cause mortality appeared consistent across the sexes, age groups, body mass index categories, and physical activity levels and across healthy participants compared with participants with preexisting cardiovascular disease or diabetes mellitus.CONCLUSIONS: Prolonged sitting is a risk factor for all-cause mortality, independent of physical activity. Public health programs should focus on reducing sitting time in addition to increasing physical activity levels.
van Uffelen J GZ, Heesch KC, Brown W. Correlates of sitting time in working age Australian women: who should be targeted with interventions to decrease sitting time? J Phys Act Health. 2012 Feb;9(2):270-87.

BACKGROUND: While there is emerging evidence that sedentary behavior is negatively associated with health risk, research on the correlates of sitting time in adults is scarce.METHODS: Self-report data from 7724 women born between 1973-1978 and 8198 women born between 1946-1951 were collected as part of the Australian Longitudinal Study on Women’s Health. Linear regression models were computed to examine whether demographic, family and caring duties, time use, health, and health behavior variables were associated with weekday sitting time.RESULTS: Mean sitting time (SD) was 6.60 (3.32) hours/day for the 1973-1978 cohort and 5.70 (3.04) hours/day for the 1946-1951 cohort. Indicators of socioeconomic advantage, such as full-time work and skilled occupations in both cohorts and university education in the mid-age cohort, were associated with high sitting time. A cluster of ‘healthy behaviors’ was associated with lower sitting time in the mid-aged women (moderate/high physical activity levels, nonsmoking, nondrinking). For both cohorts, sitting time was highest in women in full-time work, in skilled occupations, and in those who spent the most time in passive leisure.CONCLUSIONS: The results suggest that, in young and mid-aged women, interventions for reducing sitting time should focus on both occupational and leisure-time sitting.
van Uffelen JG, van Gellecum YR, Burton NW, Peeters G, Heesch KC, Brown WJ. Sitting-time, physical activity, and depressive symptoms in mid-aged women. Am J Prev Med. 2013 Sep;45(3):276-81. doi: 10.1016/j.amepre.2013.04.009.

BACKGROUND: Associations of sitting-time and physical activity with depression are unclear.PURPOSE: To examine concurrent and prospective associations between both sitting-time and physical activity with prevalent depressive symptoms in mid-aged Australian women.METHODS: Data were from 8950 women, aged 50-55 years in 2001, who completed mail surveys in 2001, 2004, 2007, and 2010. Depressive symptoms were assessed using the Center for Epidemiological Studies Depression questionnaire. Associations between sitting-time (?4 hours/day, >4-7 hours/day, >7 hours/day) and physical activity (none, some, meeting guidelines) with depressive symptoms (symptoms/no symptoms) were examined in 2011 in concurrent and lagged mixed-effect logistic modeling. Both main effects and interaction models were developed.RESULTS: In main effects modeling, women who sat >7 hours/day (OR=1.47, 95% CI=1.29, 1.67) and women who did no physical activity (OR=1.99, 95% CI=1.75, 2.27) were more likely to have depressive symptoms than women who sat ?4 hours/day and who met physical activity guidelines, respectively. In interaction modeling, the likelihood of depressive symptoms in women who sat >7 hours/day and did no physical activity was triple that of women who sat ?4 hours/day and met physical activity guidelines (OR 2.96, 95% CI=2.37, 3.69). In prospective main effects and interaction modeling, sitting-time was not associated with depressive symptoms, but women who did no physical activity were more likely than those who met physical activity guidelines to have future depressive symptoms (OR=1.26, 95% CI=1.08, 1.47).CONCLUSIONS: Increasing physical activity to a level commensurate with guidelines can alleviate current depression symptoms and prevent future symptoms in mid-aged women. Reducing sitting-time may ameliorate current symptoms.Copyright © 2013 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.
van Uffelen JG, Wong J, Chau JY, van der Ploeg HP, Riphagen I, Gilson ND, Burton NW, Healy GN, Thorp AA, Clark BK, Gardiner PA, Dunstan DW, Bauman A, Owen N, Brown WJ. Occupational sitting and health risks: a systematic review. Am J Prev Med. 2010 Oct;39(4):379-88.

CONTEXT: Emerging evidence suggests that sedentary behavior (i.e., time spent sitting) may be negatively associated with health. The aim of this study was to systematically review the evidence on associations between occupational sitting and health risks.EVIDENCE ACQUISITION: Studies were identified in March-April 2009 by literature searches in PubMed, PsycINFO, CENTRAL, CINAHL, EMBASE, and PEDro, with subsequent related-article searches in PubMed and citation searches in Web of Science. Identified studies were categorized by health outcome. Two independent reviewers assessed methodologic quality using a 15-item quality rating list (score range 0-15 points, higher score indicating better quality). Data on study design, study population, measures of occupational sitting, health risks, analyses, and results were extracted.EVIDENCE SYNTHESIS: 43 papers met the inclusion criteria (21% cross-sectional, 14% case-control, 65% prospective); they examined the associations between occupational sitting and BMI (n=12); cancer (n=17); cardiovascular disease (CVD, n=8); diabetes mellitus (DM, n=4); and mortality (n=6). The median study-quality score was 12 points. Half the cross-sectional studies showed a positive association between occupational sitting and BMI, but prospective studies failed to confirm a causal relationship. There was some case-control evidence for a positive association between occupational sitting and cancer; however, this was generally not supported by prospective studies. The majority of prospective studies found that occupational sitting was associated with a higher risk of DM and mortality.CONCLUSIONS: Limited evidence was found to support a positive relationship between occupational sitting and health risks. The heterogeneity of study designs, measures, and findings makes it difficult to draw definitive conclusions at this time.Copyright © 2010 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.Comment inAm J Prev Med. 2010 Oct;39(4):389-91.
Vandelanotte C, Sugiyama T, Gardiner P, Owen N. Associations of leisure-time internet and computer use with overweight and obesity, physical activity and sedentary behaviors: cross-sectional study. J Med Internet Res. 2009 Jul 27;11(3):e28.

BACKGROUND: Internet and computer use are increasingly common leisure-time sedentary behaviors, which have the potential to impact negatively on health outcomes. However, little is known about the extent to which adults’ Internet and computer use is associated with weight status and time spent in leisure-time physical activity.OBJECTIVE: The objective is to examine associations of leisure-time Internet and computer use with overweight and obesity, leisure-time physical activity, and other sedentary behaviors.METHODS: Participants (2650 adults living in Adelaide, Australia) completed a mail-back questionnaire including items on their height and weight, past seven day recall of leisure-time physical activity, Internet and computer use, and other leisure-time sedentary behaviors. Leisure-time Internet and computer use was categorized into no use, low use (less than three hours per week), or high use (three hours or more per week).RESULTS: Participants with low leisure-time Internet and computer use had the highest levels of educational attainment and employment, and engaged in less other sedentary behaviors when compared to participants with no or high Internet and computer use. Multinomial logistic regression, adjusted for gender, age, employment, education, other sedentary behaviors and physical activity, determined that participants with a high leisure-time Internet and computer use were 1.46 (95% CI = 1.10 – 1.93) times more likely to be overweight (BMI> or =25 and < 30 kg/m(2)) and 2.52 times more likely (95% CI = 1.82 – 3.52) to be obese (BMI> or =30 kg/m(2)), compared to those who reported no Internet and computer use in their leisure-time. Adults with high leisure-time Internet and computer use were more likely to be overweight or obese even if they were highly active in their leisure time (OR = 1.86; 95% CI = 1.21 – 2.88), as compared to participants who did not use the Internet or computer. Leisure-time physical activity levels were largely independent of Internet and computer use.CONCLUSION: These findings suggest that, apart from nutritional and physical activity interventions, it may also be necessary to decrease time spent in sedentary behaviors, such as leisure-time Internet and computer use, in order to reduce the prevalence of overweight and obesity. Future Internet interventions to reduce weight or increase physical activity may need to differentiate between participants with different levels of Internet use in order to increase their effectiveness. Longitudinal studies are required to examine further the potential causal relationships between the development of overweight and specific sedentary behaviors such as Internet and computer use.
Viir, Ragnar; Virkus, Ahti; Laiho, Kari; Rajaleid, Kristiina; Selart, Anne; Mikkelsson, Marja Trapezius muscle tone and viscoelastic properties in sitting and supine positions SJWEH Supplements 2007;(no 3):76-80;

Objectives In this study, the aim was to use the upper trapezius muscle as a representative of the musculoskeletal support system to determine the effect of changing from a sitting position to a lying position on muscle tension and whether this change could be useful in the prevention of musculoskeletal complaints. Methods Fifteen healthy right-handed female computer operators participated in this study. Myometric measurements of the upper trapezius muscle on both sides of the body were recorded for the participants while they were in a sitting position and then again in a supine position. Results Changing from a sitting position to a supine position reduced the tone and stiffness by up to one-fifth—important characteristics of the support function—in the upper trapezius muscle. Conclusions The change in the tone and stiffness of the trapezius muscle is of significance to the well-being of sedentary workers, particularly computer-terminal operators. Including recommended regular breaks of brief periods of simple, unchallenging movements while in a supine position should enhance their recovery from prolonged sitting because the support requirement on the muscles is lessened. Key terms gravity; muscle; muscle tone; prevention; sitting; sitting position; supine position; support function; trapezius muscle; trapezius muscle tone; viscoelastic property; workplace; workplace prevention
Weller I, Corey P. The impact of excluding non-leisure energy expenditure on the relation between physical activity and mortality in women. Epidemiology. 1998 Nov;9(6):632-5.

The purpose of this study was to examine the relation between physical activity and mortality in a 7-year follow-up of a sample of women more than 30 years of age (N = 6,620) from the Canada Fitness Survey cohort, which was initiated in 1981. Age-adjusted relative risks relating quartiles of average daily energy expenditure (kilocalories per kilogram of body weight per day) to mortality were estimated using logistic regression. Compared with the least active, the risk of all-cause mortality was 0.73 for those in the highest quartile (P for trend = 0.03). The associations were stronger for cardiovascular disease mortality (odds ratio = 0.51; P for trend = 0.01) and fatal myocardial infarction (odds ratio = 0.61; P for trend = 0.04) for those in the highest quartile. These relations were due mainly to the contribution of non-leisure (household chores) energy expenditure, which represented, on average, 82% of women’s total activity. The accompanying study on the same cohort by Villeneuve et al reported estimates based on a subset of leisure-time physical activity only, which underestimates the activity of many women (Villeneuve PJ, Morrison HI, Craig CL, Schaubel DE. Physical activity, physical fitness, and risk of dying. Epidemiology 1998;9;632-635). The resulting bias illustrates the importance of including non-leisure energy expenditure in the assessment of total activity. These data support the hypothesis that physical activity is inversely associated with risk of death in women.
Westerterp KR. Pattern and intensity of physical activity. Nature. 2001 Mar 29;410(6828):539.

[No abstract available.]
Whitt-Glover MC, Taylor WC, Floyd MF, Yore MM, Yancey AK, Matthews CE. Disparities in physical activity and sedentary behaviors among US children and adolescents: prevalence, correlates, and intervention implications. J Public Health Policy. 2009;30 Suppl 1:S309-34.

Regular physical activity is important for health benefits among youth, but disparities exist. This paper describes disparities in physical activity participation and sedentary behaviors among youth in the United States, provides intervention implications, and offers recommendations for future research focused on reducing disparities related to levels of physical activity. Secondary analysis of national accelerometer data showed that achievement of recommended levels of physical activity ranged across subgroups from 2% to 61%. Mean hours per day spent in sedentary behavior ranged from 5.5 to 8.5. The largest disparities were by gender and age. An improved understanding of correlates may inform the design of interventions to increase physical activity in targeted subgroups. Additional theoretically based research is needed to elucidate which factors contributing to physical activity disparities are amenable to change via intervention. To eliminate health disparities, changes in policies that have an impact on physical activity may be necessary to promote physical activity among high-risk youth.
Wiecha JL, Peterson KE, Ludwig DS, Kim J, Sobol A, Gortmaker SL. When children eat what they watch: impact of television viewing on dietary intake in youth. Arch Pediatr Adolesc Med. 2006 Apr;160(4):436-42.

OBJECTIVES: To test whether increased television viewing is associated with increased total energy intake and with increased consumption of foods commonly advertised on television, and to test whether increased consumption of these foods mediates the relationship between television viewing and total energy intake.DESIGN: Prospective observational study with baseline (fall 1995) and follow-up (spring 1997) measures of youth diet, physical activity, and television viewing. We used food advertising data to identify 6 food groups for study (sweet baked snacks, candy, fried potatoes, main courses commonly served as fast food, salty snacks, and sugar-sweetened beverages).SETTING AND PARTICIPANTS: Five public schools in 4 communities near Boston. The sample included 548 students (mean age at baseline, 11.70 years; 48.4% female; and 63.5% white).MAIN OUTCOME MEASURES: Change in total energy intake and intake of foods commonly advertised on television from baseline to follow-up.RESULTS: After adjusting for baseline covariates, each hour increase in television viewing was associated with an additional 167 kcal/d (95% confidence interval, 136-198 kcal/d; P<.001) and with increases in the consumption of foods commonly advertised on television. Including changes in intakes of these foods in regression models provided evidence of their mediating role, diminishing or rendering nonsignificant the associations between change in television viewing and change in total energy intake.CONCLUSIONS: Increases in television viewing are associated with increased calorie intake among youth. This association is mediated by increasing consumption of calorie-dense low-nutrient foods frequently advertised on television.
Wijndaele K, Brage S, Besson H, Khaw KT, Sharp SJ, Luben R, Bhaniani A, Wareham NJ, Ekelund U. Television viewing and incident cardiovascular disease: prospective associations and mediation analysis in the EPIC Norfolk Study. PLoS One. 2011;6(5):e20058. Epub 2011 May 25.

BACKGROUND: Although television viewing time is detrimentally associated with intermediate cardiovascular risk factors, the relationship with incident total (i.e. combined fatal and non-fatal) cardiovascular disease (CVD), non-fatal CVD and coronary heart disease is largely unknown. This study examined whether television viewing time is associated with these three outcomes, independently of physical activity energy expenditure and other confounding variables.METHODOLOGY/PRINCIPAL FINDINGS: A population-based cohort of 12,608 men and women (aged 61.4±9.0), free from stroke, myocardial infarction and cancer at baseline in 1998-2000 were followed up until 2007 (6.9±1.9 years). Participants self-reported education, smoking, alcohol use, antihypertensive, lipid lowering and antidepressant medication, disease history, total energy intake, sleep duration, physical activity and television viewing. BMI, waist circumference, blood pressure, triglycerides, HDL cholesterol and glycated haemoglobin (HbA(1c)) were measured by standardized procedures; a clustered metabolic risk score was constructed. Every one hour/day increase in television viewing was associated with an increased hazard for total (HR?=?1.06, 95%CI?=?1.03-1.08; 2,620 cases), non-fatal CVD (HR?=?1.06, 95%CI?=?1.03-1.09; 2,134 cases), and coronary heart disease (HR?=?1.08, 95%CI?=?1.03-1.13; 940 cases), independent of gender, age, education, smoking, alcohol, medication, diabetes status, CVD family history, sleep duration and physical activity energy expenditure. Energy intake, BMI, waist circumference, blood pressure, triglycerides, HDL cholesterol, HbA(1c) and the clustered metabolic risk score only partially mediated these associations.CONCLUSIONS: These results indicate that the most prevalent leisure time (sedentary) behaviour, television viewing, independently contributes to increased CVD risk. Recommendations on reducing television viewing time should be considered.
Wijndaele K, Brage S, Besson H, Khaw KT, Sharp SJ, Luben R, Wareham NJ, Ekelund U. Television viewing time independently predicts all-cause and cardiovascular mortality: the EPIC Norfolk study. Int J Epidemiol. 2011 Feb;40(1):150-9. Epub 2010 Jun 23.

BACKGROUND: Television viewing (TV), a highly prevalent behaviour, is associated with higher cardiovascular risk independently of physical activity. The relationship with mortality, however, is relatively unknown.METHODS: We examined the prospective relationship between TV time and all-cause, cardiovascular and cancer mortality in a population-based cohort [The European Prospective Investigation into Cancer and Nutrition (EPIC), Norfolk] of 13?197 men and women {age [SD (standard deviation)]: 61.5?±?9.0 years}. Participants were free from stroke, myocardial infarction and cancer at baseline in 1998-2000 and were followed up for death ascertainment until 2009 (9.5?±?1.6 years). TV time, total physical activity energy expenditure (PAEE), education level, smoking status, alcohol consumption, anti-hypertensive and lipid-lowering medication use, participant and family history of disease and total energy intake were self-reported; height and weight were measured by standardized procedures. Hazard ratios (HRs) [95% confidence interval (CI)] for mortality were estimated per 1-h/day increase in TV.RESULTS: Each 1-h/day increase in TV time was associated with increased hazard of all-cause (HR?=?1.04, 95% CI?=?1.01-1.09; 1270 deaths) and cardiovascular (HR?=?1.07, 95% CI?=?1.01-1.15; 373 deaths), but not cancer mortality (HR?=?1.04, 95% CI?=?0.98-1.10; 570 deaths). This was independent of gender, age, education, smoking, alcohol, medication, diabetes history, family history of cardiovascular disease and cancer, body mass index (BMI) and PAEE. They were similar when stratified by gender, age, education, BMI and PAEE. The population-attributable fraction for all-cause mortality comparing the highest TV tertile (>3.6?h/day) with the lowest (<2.5?h/day) was 5.4%.CONCLUSIONS: These findings suggest that public health recommendations should consider advising a reduction in TV time, a predominant leisure activity in modern society, in addition to advocating physical activity.
Wijndaele K, Duvigneaud N, Matton L, Duquet W, Delecluse C, Thomis M, Beunen G, Lefevre J, Philippaerts RM. Sedentary behaviour, physical activity and a continuous metabolic syndrome risk score in adults. Eur J Clin Nutr. 2009 Mar;63(3):421-9. Epub 2007 Oct 31.

OBJECTIVE: The association of sedentary behaviour and leisure time physical activity with a validated continuous metabolic syndrome risk score was investigated in adults.SUBJECTS/METHODS: A number of 992 adults (559 men) without cardiovascular disease or diabetes. Subjects reported time spent in leisure time physical activity and television watching/computer activities. A validated metabolic syndrome risk score, based on waist circumference, triglycerides, blood pressure, fasting plasma glucose and high-density lipoprotein cholesterol, was used. The metabolic syndrome risk score and time spent in sedentary behaviour and physical activity were analysed as continuous variables using multiple linear regression.RESULTS: Metabolic syndrome risk was positively associated with time spent watching television/computer activities, irrespective of physical activity level, and after adjustment for age, education level, smoking status and dietary intake in women aged > or =45 years (beta=0.184, P<0.05). Independent of the time being sedentary, moderate to vigorous leisure time physical activity was inversely associated with metabolic syndrome risk in men (<45 years: beta=-0.183, P<0.01; > or =45 years: beta=-0.192, P<0.01) and women aged > or =45 years (beta=-0.203, P<0.01).CONCLUSIONS: Although cross-sectional, the present results support inclusion of efforts to decrease sedentary behaviour in metabolic syndrome prevention strategies for women aged > or =45 years, besides promotion of moderate to vigorous physical activity, since both behavioural changes might show additional effects.
Wijndaele K, Healy GN, Dunstan DW, Barnett AG, Salmon J, Shaw JE, Zimmet PZ, Owen N. Increased cardiometabolic risk is associated with increased TV viewing time. Med Sci Sports Exerc. 2010 Aug;42(8):1511-8.

PURPOSE: Television viewing time, independent of leisure time physical activity, has cross-sectional relationships with the metabolic syndrome and its individual components. We examined whether baseline and 5-yr changes in self-reported television viewing time are associated with changes in continuous biomarkers of cardiometabolic risk (waist circumference, triglycerides, HDL-cholesterol, systolic and diastolic blood pressure, fasting plasma glucose, and a clustered cardiometabolic risk score) in Australian adults.METHODS: The Australian Diabetes, Obesity and Lifestyle Study (AusDiab) is a prospective, population-based cohort study with biological, behavioral, and demographic measures collected in 1999-2000 and 2004-2005. Noninstitutionalized adults aged > or =25 yr were measured at baseline (11,247; 55% of those completing an initial household interview); 6400 took part in the 5-yr follow-up biomedical examination, and 3846 met the inclusion criteria for this analysis. Multiple linear regression analysis was used, and unstandardized B coefficients (95% confidence intervals (CI)) are provided.RESULTS: Baseline television viewing time (10 h.wk-1 unit) was not significantly associated with change in any of the biomarkers of cardiometabolic risk. Increases in television viewing time over 5 yr (10 h.wk-1 unit) were associated with increases in waist circumference (men: 0.43 cm, 95% CI = 0.08-0.78 cm, P = 0.02; women: 0.68 cm, 95% CI = 0.30-1.05, P < 0.001), diastolic blood pressure (women: 0.47 mm Hg, 95% CI = 0.02-0.92 mm Hg, P = 0.04), and the clustered cardiometabolic risk score (women: 0.03, 95% CI = 0.01-0.05, P = 0.007). These associations were independent of baseline television viewing time and baseline and change in physical activity and other potential confounders.CONCLUSIONS: These findings indicate that an increase in television viewing time is associated with adverse cardiometabolic biomarker changes. Further prospective studies using objective measures of several sedentary behaviors are required to confirm causality of the associations found.
Wijndaele K, Lynch BM, Owen N, Dunstan DW, Sharp S, Aitken JF. Television viewing time and weight gain in colorectal cancer survivors: a prospective population-based study. Cancer Causes Control. 2009 Oct;20(8):1355-62. Epub 2009 May 17.

OBJECTIVE: To investigate the prospective relationships between television viewing time and weight gain in the 3 years following colorectal cancer diagnosis for 1,867 colorectal cancer survivors (body mass index (BMI) > or = 18.5 kg/m(2)).METHODS: BMI, television viewing time, physical activity, and socio-demographic and clinical covariates were assessed at baseline (5 months), 24 months and 36 months post-diagnosis. Multiple linear regression was used to study independent associations between baseline television viewing time and BMI at 24 and 36 months post-diagnosis.RESULTS: At both follow-up time points, there was a significant increase in mean BMI for participants reporting > or =5 h/day of television viewing compared to those watching <3 h/day at baseline (24 months: 0.72 kg/m(2) (0.31, 1.12), p < 0.001; 36 months: 0.61 kg/m(2) (0.14, 1.07), p = 0.01), independent of baseline BMI, gender, age, education, marital status, smoking, cancer site, cancer disease stage, treatment mode and co-morbidities. Additional adjustment for baseline physical activity did not change results.CONCLUSIONS: These findings suggest that a greater emphasis on decreasing television viewing time could help reduce weight gain among colorectal cancer survivors. This, in turn, could contribute to a risk reduction for co-morbid conditions such as type 2 diabetes and cardiovascular disease.
Wijndaele K, Orrow G, Ekelund U, Sharp SJ, Brage S, Griffin SJ, Simmons RK. Increasing objectively measured sedentary time increases clustered cardiometabolic risk: a 6 year analysis of the ProActive study. Diabetologia. 2014 Feb;57(2):305-12. doi: 10.1007/s00125-013-3102-y. Epub 2013 Nov 6.

AIMS/HYPOTHESIS: We aimed to quantify the associations between change in objectively measured sedentary and moderate-to-vigorous physical activity (MVPA) times and self-reported television viewing over 6 years and change in a clustered cardiometabolic risk score (CCMR), including and excluding waist circumference (CCMR without adiposity component, CCMR no adip ), and its individual components, among the adult children of people with type 2 diabetes.METHODS: In 171 adults (mean ± SD age 42.52?±?6.30 years; 46% men) with a parental history of diabetes (ProActive UK), physical activity accelerometer measures and self-reported television viewing were assessed at baseline and a mean ± SD of 6.27?±?0.46 years later. Associations between change in sedentary time, MVPA time and television viewing and cardiometabolic risk and mediation by adiposity change were examined by multiple linear regression and the product of coefficients method, respectively.RESULTS: Greater increases in sedentary time (h/day) were associated with larger increases in clustered cardiometabolic risk (CCMR: 0.08 [95% CI 0.01, 0.15]; CCMR no adip : 0.08 [0.01, 0.16]) and triacylglycerol (0.15 [0.01, 0.29]), independent of baseline sedentary and MVPA times, change in MVPA time and other confounders. No evidence was found for mediation by change in waist circumference and BMI for the associations with CCMR no adip and triacylglycerol. Greater increases in MVPA time (h/day) were associated with larger decreases in waist circumference (-3.86 [-7.58, -0.14]), independently of baseline MVPA and sedentary times, change in sedentary time and other confounders. Television viewing was not independently associated with any of the cardiometabolic outcomes.CONCLUSIONS/INTERPRETATION: Increasing sedentary time is independently related to increasing clustered cardiometabolic risk and triacylglycerol in adults at high risk of developing diabetes. Strategies to prevent diabetes might target reducing sedentary time. Trial registration ISRCTN61323766.
Wilmot EG, Edwardson CL, Achana FA, Davies MJ, Gorely T, Gray LJ, Khunti K, Yates T, Biddle SJ. Sedentary time in adults and the association with diabetes, cardiovascular disease and death: systematic review and meta-analysis. Diabetologia. 2012 Aug 14. [Epub ahead of print]

AIMS/HYPOTHESIS: Sedentary (sitting) behaviours are ubiquitous in modern society. We conducted a systematic review and meta-analysis to examine the association of sedentary time with diabetes, cardiovascular disease and cardiovascular and all-cause mortality.METHODS: Medline, Embase and the Cochrane Library databases were searched for terms related to sedentary time and health outcomes. Cross-sectional and prospective studies were included. RR/HR and 95% CIs were extracted by two independent reviewers. Data were adjusted for baseline event rate and pooled using a random-effects model. Bayesian predictive effects and intervals were calculated to indicate the variance in outcomes that would be expected if new studies were conducted in the future.RESULTS: Eighteen studies (16 prospective, two cross-sectional) were included, with 794,577 participants. Fifteen of these studies were moderate to high quality. The greatest sedentary time compared with the lowest was associated with a 112% increase in the RR of diabetes (RR 2.12; 95% credible interval [CrI] 1.61, 2.78), a 147% increase in the RR of cardiovascular events (RR 2.47; 95% CI 1.44, 4.24), a 90% increase in the risk of cardiovascular mortality (HR 1.90; 95% CrI 1.36, 2.66) and a 49% increase in the risk of all-cause mortality (HR 1.49; 95% CrI 1.14, 2.03). The predictive effects and intervals were only significant for diabetes.CONCLUSIONS/INTERPRETATION: Sedentary time is associated with an increased risk of diabetes, cardiovascular disease and cardiovascular and all-cause mortality; the strength of the association is most consistent for diabetes.
Wong SL, Leatherdale ST. Association between sedentary behavior, physical activity, and obesity: inactivity among active kids. Prev Chronic Dis. 2009 Jan;6(1):A26. Epub 2008 Dec 15.

INTRODUCTION: Sedentary behavior and physical activity are not mutually exclusive behaviors. The relative risk of overweight for adolescents who are highly sedentary and highly physically active is unclear. A better understanding of the relationship between sedentary behaviors, physical activity, and body mass index (BMI) would provide insight for developing interventions to prevent or reduce overweight.METHODS: Using the physical activity module of the School Health Action, Planning and Evaluation System (SHAPES), we collected data from 25,060 students in grades 9 through 12 from 76 secondary schools in Ontario, Canada. Sex-specific logistic regression analyses were performed to examine how BMI, weight perceptions, social influences, team sports participation, and smoking behavior were associated with being 1) high active-high sedentary, 2) low active-low sedentary, and 3) low active-high sedentary.RESULTS: Low active-high sedentary boys were more likely to be overweight than high active-low sedentary boys (adjusted odds ratio [AOR], 1.60; 95% confidence interval [CI], 1.01-2.58). When compared with high active-low sedentary girls, girls who were low active-high sedentary (OR, 2.24; 95% CI, 1.23-4.09) or high active-high sedentary (OR, 1.91; 95% CI, 1.01-3.61) were more likely to be overweight.CONCLUSION: Sedentary behavior may moderate the relationship between physical activity and overweight. Developing a better understanding of sedentary behavior in relation to physical activity and overweight is critical for preventing and reducing overweight among youth.
Wong, T.S., Gaston, A., De Jesus, S., & Prapavessis, H . The utility of a protection motivation theory framework for understanding sedentary behavior. Wong, T.S., Gaston, A., De Jesus, S., & Prapavessis, H (2016). The utility of a protection motivation theory framework for understanding sedentary behavior. Health Psychology and Behavioral Medicine, 4:1, 29-48. Doi: 10.1080/21642850.2015.112833

Multilevel determinants of sedentary behavior (SB), including constructs couched within evidence-based psychological frameworks, can contribute to more efficacious interventions designed to decrease sitting time. This study aimed to: (1) examine the factor structure and composition of sedentary- derived protection motivation theory (PMT) constructs and (2) determine the utility of these constructs in predicting general and leisure sedentary goal intention (GI), implementation intention (II), and self-reported SB. Sedentary-derived PMT (perceived severity, PS; perceived vulnerability, PV; response efficacy, RE; self-efficacy, SE), GI, and II constructs, and a modified SB questionnaire were completed by undergraduate students (n=596). SE was broken into three psychological (productive, focused, tired), and two situational (studying, leisure) constructs to capture the main barriers to reducing sitting time. After completing socio- demographics and the PMT items, participants were randomized to complete general or leisure GI and II. Based on model assignment, they completed either the general or leisure SB questionnaire one week later. Irrespective of model, exploratory followed by confirmatory factor analysis revealed that the PMT items grouped into eight coherent and interpretable factors consistent with the theory’s threat and coping appraisal tenets: PV, PS, RE, and five scheduling SE constructs (tired, productive/ focused, TV/video games/computer, studying at home, studying in library/Wi-Fi area). Using linear regression, general and leisure models predicted 5% and 1% of the variance in GI, 10% and 16% of the variance in II, and 3% and 1% of the variance in SB, respectively. Variables that made unique and significant contributions were: RE (general) and SE (leisure) for goal intention; PV and RE (general), PV, RE, and SE (leisure) for implementation intention; and only goal intention (leisure) for SB. Support now exists for the tenability of an eight-factor PMT sedentary model and its utility in predicting II and to a lesser extent GI and behavior.
Y?ld?r?m M, Verloigne M, de Bourdeaudhuij I, Androutsos O, Manios Y, Felso R, Kovács É, Doessegger A, Bringolf-Isler B, te Velde SJ, Brug J, Chinapaw MJ. Study protocol of physical activity and sedentary behaviour measurement among schoolchildren by accelerometry--cross-sectional survey as part of the ENERGY-project. BMC Public Health. 2011 Mar 25;11:182.

BACKGROUND: Physical activity and sedentary behaviour among children should be measured accurately in order to investigate their relationship with health. Accelerometry provides objective and accurate measurement of body movement, which can be converted to meaningful behavioural outcomes. The aim of this study was to evaluate the best evidence for the decisions on data collection and data processing with accelerometers among children resulting in a standardized protocol for use in the participating countries.METHODS/DESIGN: This cross-sectional accelerometer study was conducted as part of the European ENERGY-project that aimed to produce an obesity prevention intervention among schoolchildren. Five countries, namely Belgium, Greece, Hungary, Switzerland and the Netherlands participated in the accelerometer study. We used three different Actigraph models–Actitrainers (triaxial), GT3Xs and GT1Ms. Children wore the device for six consecutive days including two weekend days. We selected an epoch length of 15 seconds. Accelerometers were placed at children’s waist at the right side of the body in an elastic belt. In total, 1082 children participated in the study (mean age = 11.7 ± 0.75 y, 51% girls). Non-wearing time was calculated as periods of more than 20 minutes of consecutive zero counts. The minimum daily wearing time was set to 10 hours for weekdays and 8 hours for weekend days. The inclusion criterion for further analysis was having at least three valid weekdays and one valid weekend day. We selected a cut-point (count per minute (cpm)) of <100 cpm for sedentary behaviour, <3000 cpm for light, <5200 cpm for moderate, and >5200 cpm for vigorous physical activity. We also created time filters for school-time during data cleaning in order to explore school-time physical activity and sedentary behaviour patterns in particular.DISCUSSION: This paper describes the decisions for data collection and processing. Use of standardized protocols would ease future use of accelerometry and the comparability of results between studies.
Yates T, Khunti K, Wilmot EG, Brady E, Webb D, Srinivasan B, Henson J, Talbot D, Davies MJ. Self-reported sitting time and markers of inflammation, insulin resistance, and adiposity. Am J Prev Med. 2012 Jan;42(1):1-7.

BACKGROUND: Sedentary behavior is emerging as an independent risk factor for chronic disease; however, potential mechanisms underpinning these observations are not well understood.PURPOSE: This study aimed to investigate the association of self-reported weekday sitting time with biomarkers linked to chronic low-grade inflammation, insulin resistance, and adiposity.METHODS: This study reports data from individuals attending a diabetes screening program, United Kingdom, 2004-2007; analysis was conducted in 2010. Sitting time and physical activity were measured using the International Physical Activity Questionnaire; biochemical outcomes included fasting and 2-hour postchallenge glucose, fasting insulin, C-reactive protein (CRP), leptin, adiponectin, and interleukin-6 (IL-6).RESULTS: This study included 505 (female=46%; South-Asian ethnicity=19%, aged 59±10 years, BMI=29.5±4.7) individuals with valid sitting data. Increased sitting time was positively associated with fasting insulin, leptin, leptin/adiponectin ratio, CRP, and IL-6 in women, but not men, after adjustment for age, ethnicity, social deprivation, and smoking and medication status; interaction analysis revealed that the gender-specific differences were significant. The associations for women remained significant after additional adjustment for total moderate- to vigorous-intensity physical activity; however all associations were attenuated when further adjusted for BMI. There was no association between sitting time and glycemic status.CONCLUSIONS: Total self-reported weekday sitting time was associated with biomarkers linked to chronic low-grade inflammation and poor metabolic health in women, but not men, independent of physical activity.Copyright © 2012 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.
Yates T, Wilmot EG, Davies MJ, Gorely T, Edwardson C, Biddle S, Khunti K. Sedentary behavior: what's in a definition? Am J Prev Med. 2011 Jun;40(6):e33-4; author reply e34.

[No abstract available.]
Zimmerman FJ, Bell JF. Associations of television content type and obesity in children. Am J Public Health. 2010 Feb;100(2):334-40. Epub 2009 Dec 17.

OBJECTIVES: We tested the associations of content types of children’s television viewing with subsequent body mass index (BMI) to assess the plausibility of different causal pathways.METHODS: We used time-use diary data from the Panel Survey of Income Dynamics to measure television viewing categorized by format and educational and commercial content. Analyses were stratified by age because children younger than 7 years are less able to understand the persuasive intent of advertising. BMI z scores in 2002 were regressed on television viewing, sociodemographic variables, mother’s BMI, and BMI in 1997 (for older children only).RESULTS: Among children aged 0 to 6 years in 1997, commercial viewing in 1997 was significantly associated with BMI z scores in 2002 in fully adjusted regressions. Among children older than 6 years, commercial viewing in 2002 was associated with 2002 BMI. These results were robust after adjustment for exercise and eating while watching television.CONCLUSIONS: The evidence does not support the contention that television viewing contributes to obesity because it is a sedentary activity. Television advertising, rather than viewing per se, is associated with obesity.


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