From the American Journal of Preventive Medicine:
Associations of sitting-time and physical activity with depression are unclear.
To examine concurrent and prospective associations between both sitting-time and physical activity with prevalent depressive symptoms in mid-aged Australian women.
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.
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).
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.
For links to other sedentary behaviour studies, please visit the SBRN Research Database.
Today’s guest post comes from PhD student Bethany Howard. You can find out more about Bethany at the bottom of this post. The study that she is discussing was recently published in MSSE, and can be found here.
I am sure by now you have all heard the messages to avoid your chair and the increased risk of premature death it may be kindly bestowing on you. Indeed there are slogans out there such as “your chair is sending you to an early grave”, “make a stand”, “sitting is the new smoking” and big corporations that promote this important rapidly evolving area of research – that is the study of the health consequences of “too much sitting”.
What do we know?
It’s important to appreciate that these messages about the hazards of sitting are not entirely new – as early as the 1950’s physicians were advocating breaks from sitting. Homans (1954) suggested that the “Such matters are important enough to suggest the advisability of making movement of the toes, feet and lower legs when one is sitting for long periods and of getting up and exercising when opportunity offers.” Such recommendations were drawn from cases of thrombosis – the formation of a blood clot that obstructs blood flow – with prolonged sitting at the theatre, whist watching TV and during travel.
Today the research initiated from such early work is now evident in the recommendations when we fly. For those of you who are avid jetsetters you will be familiar with the announcement to “get up and move around to reduce the risk of deep vein thrombosis (VT)”. There is now evidence to suggest that this increased risk extends to prolonged bus travel and prolonged workplace sitting. But the question we wanted to ask with our experimental study published recently in Medicine & Science and Sports & Exercise was:
What are the potential reasons for this increased risk?
Virchow describes three components that contribute to the risk of VT, known commonly as Virchows Triad: Impaired blood flow, Hyper-coagulation and Disturbed Endothelium. Of these, there is substantial evidence linking sitting to impaired blood flow, limited evidence on hypercoagulation and little or no evidence for possible effects on the endothelium. The majority of studies that have been conducted in this area have focused on air travel. Although high amounts of sitting are present, air travel does not provide the typical environment in which sitting accumulates in our daily lives.
What did we do?
In order to address these knowledge gaps, we used an experimental study design to examine the effects of sitting (uninterrupted) on markers of thrombosis, specifically markers that relate to clot formation (through haemostasis) and blood viscosity. We then compared these effects to interrupted sitting, to assess whether breaks involving walking were indeed effective at reducing thrombotic risk. To do this we undertook an acute randomized cross-over trial design with subjects being their own controls. The trial consisted of 3 conditions all of which lasted for 7 hours:
1) Uninterrupted sitting
2) Sitting interrupted by light-intensity walking breaks
3) Sitting interrupted by moderate-intensity walking breaks
The two different intensity activity break conditions were incorporated into the study design to determine if there is an intensity effect of the breaks. That is, for a benefit to be seen, do the breaks need to be of a higher intensity? Earlier observational work from our group using objective activity monitoring suggested that the intensity wasn’t as important – having breaks, and frequently seemed most important.
What did we find?
For the common blood viscosity markers (plasma volume, hematocrit, hemoglobin, red blood cells) breaks were beneficial irrespective of the intensity. That is, with the introduction of breaks in sitting time blood viscosity appeared to be reduced. This is likely to have improved blood flow, one of three elements of Virchows triad. Continue Reading
The American College of Sports Medicine will be hosting their annual scientific meeting in Indianapolis, USA, this week, and there is a wealth of sedentary behaviour research on the program. You can find a full list of the presentations related to sedentary behaviour here.
The below presentations will be led by members of SBRN. If you are giving a presentation related to sedentary behaviour at ACSM or another conference, send the presentation time and location to Travis Saunders at tsaunders (at) cheo (dot) on (dot) ca.
Sedentary/active Behaviors And Cardiometabolic Risk: Protective Effects Of Sleep Duration, Nhanes 2005-2006. Matthew P. Buman, Elisabeth A. H. Winkler, Jonathan M. Kurka, Eric B. Hekler, Neville Owen, Barbara E. Ainsworth, Genevieve N. Healy, Paul A. Gardiner. Session: Thematic Poster B-18. Sedentary Behavior: Effects on Health Wednesday, May 29, 2013 1:00 – 3:00 PM
Sedentary Behaviour, Visceral Fat And Cardiometabolic Risk: 6-year Longitudinal Study From The Quebec Family Study. Travis J. Saunders, Mark S. Tremblay, Jean-Pierre Després, Claude Bouchard, Angelo Tremblay, Jean-Philippe Chaput. Session: Thematic Poster B-18. Sedentary Behavior: Effects on Health Wednesday, May 29, 2013 1:00 – 3:00 PM.
Sedentary Behavior and Cardiometabolic Risk: Emerging Experimental Evidence. SBRN members presenting during this session include Neville Owen (Chair), Sarah Kozey-Keadle (Does Reducing Sedentary Behavior Enhance the Benefits of Exercise?), Travis Saunders (The Metabolic and Behavioral Impact of One Day of Prolonged Sitting in Children and Youth) and David Dunstan (Understanding the Acute and Cumulative Metabolic Effects of Prolonged Sitting in Adults).
Objective: 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.
Design and Methods: The hypothesis was that a 1-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/m2, n = 10 Lean BMI < 25 kg/m2, n = 15 Overweight 25 < BMI < 30 kg/m2, n = 11 Obese BMI > 30 kg/m2) volunteered to have their traditional desk replaced with a treadmill desk to promote physical activity for 1 year.
Results: 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 3,353 ± 1,802 activity units (AU)/day to, at 6 months, 4,460 ± 2,376 AU/day (P < 0.001), and at 12 months, 4,205 ± 2,238 AU/day (P < 0.001). Access to the treadmill desks was associated with significant decreases in daily sedentary time (zero activity) from at baseline 1,020 ± 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.
Conclusions: Access to treadmill desks may improve the health of office workers without affecting work performance.
A list of other studies on the health impact of sedentary behaviour can be found in the SBRN Research Database.
The 2014 Global Summit on the Physical Activity of Children — “The Power to Move Kids” — which takes place in Toronto from May 19th-22nd, 2014, will bring together those who are working to resolve the growing childhood physical inactivity crisis. Anyone whose work touches physical activity for children, including researchers, practitioners and policy-makers, should count this among the must-attend events for 2014.
Please see below for some updates on the 2014 Summit.
Summit Registration is Now Open!
We are off and running – registration for the 2014 Global Summit on the Physical Activity of Children and Youth is now open. Secure your attendance at this must-attend event for anyone whose work touches childhood physical activity.
Call For Abstracts is Online
Share your expertise with an international audience and be part of the resolution of the global childhood inactivity crisis.
The call for abstract submissions is now open for oral presentations, promising practice workshops (sharing successes) and poster presentations with either a research or practice focus.
Measuring Muscle Visco-Elasticity in Horizontal Bed Rest Model for Better Understanding of Sedentary Life Style
R. Viir, Institute of Exercise Biology and Physiotherapy, University of Tartu, TartuEstonia
RehabCenter, RheumatismFoundationHospital, Heinola, Finland
M. Pääsuke, Institute of Exercise Biology and Physiotherapy, University of Tartu, TartuEstonia
K. Rajaleid, Center for Health Equity Studies, StockholmUniversity/ Karolinska Institutet, Stockholm, Sweden
*Note: The source for this paper is the 2008 ISU 12th Annual Symposium – ‘Space Solutions to Earth’s Global Challenges’
The aim of this study was to use the upper trapezius muscle as a representative of the musculoskeletal support system to determine the effect on muscle tension due changing from upright position to a lying position and whether this change could be useful in the prevention of musculoskeletal disorders. Twenty two female subjects participated in this study. Myometric measurements of the upper trapezius muscle on both sides of the body were recorded in a standing, sitting and supine position. Changing from upright positions to a supine position reduced the upper trapezius muscle support function by up to one fifth as characterized with diminishing of muscle tone and stiffness. The change in tone and stiffness of the trapezius muscle is of significance to the well being of sedentary workers. Introducing regular brief breaks of simple unchallenging movements while being in a supine position should enhance recovery from prolonged sitting.
Prevention magazine recently featured a list of 100 ways to break up your sedentary time on. From their website:
1. Hide your remote. If you must watch TV, at least stand up to change the channel.
2. When cooking or baking, ditch the hand mixer and use a wooden spoon instead.
3. Take each family member’s laundry upstairs separately.
4. When tidying up, put things away in multiple small trips rather than one big haul.
5. Chop fresh vegetables instead of buying frozen ones.
6. Invest in quality pots and pans; the heavier they are, the more energy it’ll take to use them.
7. Paint, hang curtains, or finish any other home-improvement task on your to-do list.
8. Stand up and march during your favorite TV shows. (Try our Couch-Potato Workout.)
9. Rather than yell toward family members in other rooms, walk over to talk.
10. Stand while styling your hair and putting on makeup.
11. Walk around your home, yard, or neighborhood while on the phone.
12. Hand-wash dishes instead of using the dishwasher.
13. Wash your car instead of taking it through the car wash.
14. Put most-used items on top or bottom shelves so you have to reach for them.
15. Leave your cell phone in one location, so when you need it, you must go to it.
16. Start a compost pile in your yard.
17. Help your kids clean their rooms.
18. Organize a closet.
19. Rake the leaves as a family.
20. Give the delivery guy a break; when you order food in, pick it up yourself.
21. Take a shower instead of a bath.
22. Walk to the mailbox instead of checking the mail from your car.
23. Plant or weed a garden or care for indoor plants.
24. Ask for the paper to be left at the end of your driveway instead of by your front door.
25. Give your dog a bath instead of paying someone else to do it.
26. Instead of sitting and reading, listen to books on tape as you walk, clean, or garden.
27. Preset the timer on your TV to turn off after an hour to remind you to do something more active.
28. Slide a small trampoline under your couch and pull it out for Real Housewives marathons.
29. Put up more Christmas lights.
30. The next time it snows, up your karma and shovel your neighbor’s sidewalk too.
31. Turn on tunes and dance while cooking.
Below is a survey asking SBRN members about their views on the future of the organization, and whether or not the group should formally become a part of the International Society for Physical Activity and Health. Please take 2-5 minutes to complete the survey, as the results will determine the structure and function of the organization in the coming years. Thanks for your time!
Create your free online surveys with SurveyMonkey, the world’s leading questionnaire tool.
Earlier this year SBRN published an updated definition of the terms “sedentary” and “sedentary behaviour”, which was published in the journals Applied Physiology, Nutrition and Metabolism and Movement & Sport Sciences – Science & Motricité. The definition was originally published in both English (here) and French (here). The definition has now been translated into Spanish and Portuguese by Ana Lúcia André with help from Verónica Varela Mato.
You can find links to the translated definitions below.
The definition can be cited as:
Sedentary Behaviour Research Network. 2012. Standardized use of the terms “sedentary” and “sedentary behaviours”. Appl Physiol Nutr Metab. 37: 540–542.
If you are interested in helping to translate this definition of sedentary behaviour into another language, please contact us through our contact page.
School of Physiotherapy and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia
Curtin University is the largest university in Western Australia with a strong international focus. The School of Physiotherapy has a reputation for world class applied research and multidisciplinary collaborations. A growing number of research projects have been developed around sedentary behaviour/physical activity, technology and health – for example interventions for children and adolescents, interventions for office workers and large longitudinal epidemiological studies in children/young adults and ‘baby boomers’. These projects are mainly funded by the National Health and Medical Research Council of Australia and involve collaborations with researchers across Australia as well as Europe and North America. The research group is expanding and this creates an exciting opportunity for early career postdocs to join the team and develop as emerging leaders.
We are looking for enthusiastic, competent candidates able to work well with colleagues. Clear, critical thinking, strong conceptual and analytical background, and excellent writing skills are important, along with experience in sedentary behaviour and physical activity measurement. An earned doctorate in a related discipline is required along with strong letters of support from three colleagues/supervisors.
The role will include working with the team on existing projects to capture high quality data, data processing and analyses, and preparing and leading manuscripts and conference presentations. The role will also provide opportunities to develop grant writing and student supervision skills. Postdocs will be mentored by the team and encouraged to develop their own related research interests.
The appointment opportunities are flexible with 1-3 year contracts available. Competitive remuneration commensurate with qualifications will be provided (AUD70,000-80,000pa) along with leave and superannuation entitlements.
Further information is available from: Professor Leon Straker (L.Straker@curtin.edu.au) and Dr Rebecca Abbott (firstname.lastname@example.org; 14thDecember – 21stJanuary 2013 while Leon is on leave)
Click here for further background information on the post-doc positions.