Category: In The News
A systematic review and meta-analysis on the link between sedentary time and health outcomes in adults that was published today is receiving significant attention in the media. The title of the paper is, “Sedentary Time and Its Association With Risk for Disease Incidence, Mortality, and Hospitalization in Adults: A Systematic Review and Meta-analysis,” and was published in the Annals of Internal Medicine today. Note: several SBRN members are among the authors on the paper.
According to Dr. David Alter, lead researcher of the study and a senior scientist at the Toronto Rehabilitation Institute, “More than one half of an average person’s day is spent being sedentary — sitting, watching television or working at a computer. Our study finds that despite the health-enhancing benefits of physical activity, this alone may not be enough to reduce the risk for disease.”
Click on the links below to follow media coverage on this study:
- Excessive sitting linked to disease, premature death – Globe & Mail
- Sitting for too long can kill you, even if you exercise: study – CBC
- Too much sitting raises risk of death, even if you exercise – Full Time Whistle
- Sitting All Day Sitting Linked To Disease, Premature Death Even With Regular Exercise – Huffington Post
- Sitting on your butt too much may be deadly: study – Metro
- Too Much Sitting Linked to Increased All-Cause Mortality – Medscape
- Sitting too long increases risk of dying early – SMN Weekly
- Even with exercise, excessive sitting may be deadly – Missions Record
- Even with regular exercise, excessive sitting linked to disease, premature death – News 1130
- Even for the active, a long sit shortens life and erodes health – LA Times
- Exercising regularly WON’T offset the risk of sitting for long periods of time: An hour of activity a day isn’t enough to stave off heart disease, diabetes and cancer, study finds – Daily Mail UK
- It Doesn’t Matter How Much You Exercise If You Also Do This – Time
Biswas A, Oh PI, Faulkner GE, Bajaj RR, Silver MA, Mitchell MS, Alter DA. Sedentary Time and Its Association With Risk for Disease Incidence, Mortality, and Hospitalization in Adults: A Systematic Review and Meta-analysis. Ann Intern Med. 2015 Jan 20;162(2):123-132. doi: 10.7326/M14-1651.
Today’s post comes from Mai Chinapaw and Teatske Altenburg. Their lab website can be found here.
A recent commentary by Chinapaw et al. (Prev Med 2014) critically discussed the current evidence on the association between sedentary behaviour and cardiometabolic health in children. The authors conclude that in children, there is no convincing evidence yet on the association between sedentary behaviour and cardiometabolic health. One of the highlighted challenges to advance this field is improving the measurement of sedentary behaviour including total sedentary time and sedentary time accumulated in bouts. Two recent papers examined this important issue.
The first paper (Chinapaw et al., PLoS ONE 2014) aimed to establish evidence-based accelerometer data reduction criteria for assessment of sedentary behaviour patterns in children. This is the first study that examined the influence of data reduction procedures on the number or duration of sedentary bouts in children. The authors formulated the following recommendations: 1) a minimum of 60 minutes of consecutive zeros as the most realistic criterion for non-wear time; and 2) including at least six days with minimum eight valid hours to characterize children’s usual total sedentary time and sedentary time accumulated in bouts, preferably including one weekend day.
The second paper (Altenburg et al., Prev Med 2015) examined occurrence and durations of bouts based on various definitions (bouts of at least 5, 10, 20 or 30 min, allowing 0, 30 or 60 sec >100cpm) in 10-12 year old children. Estimates of sedentary time accumulated in bouts varied largely between the different bout definitions. Generally, children sat mostly in sedentary bouts of at least 5 min, while 20 min bouts were rare. For none of the operational definitions the authors found convincing evidence for a cross-sectional association with cardiometabolic health indicators in 10-12 year old children. However, more significant associations appeared when allowing no tolerance (i.e. zero sec >100cpm). Therefore, the authors recommend that no tolerance should be allowed within a sedentary bout.
Both papers emphasise the need for standardized definitions of sedentary bouts as well as a consensus regarding accelerometer data-reduction criteria to advance the field of sedentary behaviour and the potential associated health risk. Moreover, sedentary behaviour researchers cannot rely on accelerometer data reduction procedures established for assessing physical activity.
- Chinapaw MJM, Altenburg TM, Brug, J (2014). Sedentary behaviour and health in children – Evaluating the evidence. Prev Med 70: 1-2.
- Chinapaw MJM, de Niet M, Verloigne M, De Bourdeaudhuij I, Brug J, Altenburg TM (2014). From sedentary time to sedentary patterns: accelerometer data reduction decisions in youth. PLoS ONE 9(11): e111205. doi:10.1371/journal.pone.0111205.
- Altenburg TM, de Niet M, Verloigne M, De Bourdeaudhuij I, Androutsos O, Manios Y, Kovacs E, Bringolf-Isler B, Brug J, Chinapaw MJM (2015). Occurrence and duration of various operational definitions of sedentary bouts and cross-sectional associations with cardiometabolic health indicators: the ENERGY-project. Prev Med 71: 101-106.
On the 8th and 9th of June 2015, a workshop is organised on determinants of sedentary behaviour across the life course, as a satellite of the ISBNPA annual meeting. This workshop is organised by Dr. Sebastien Chastin and Prof. Greet Cardon, on behalf of the DEDIPAC consortium. DEDIPAC (Determinants of Diet and Physical Activity) aims to establish a European trans-disciplinary research network with a joint research agenda and it also tries to build capacity to advance understanding of the complex interplay of the numerous determinants of sedentary behaviours.
Reducing sedentary behaviour is a public health challenge internationally. Currently, there is disparate and limited knowledge about the determinants of sedentary behaviour across the life course to inform interventions. This workshop will bring together epidemiologists, psychologists, clinicians, economists, rehabilitation, life, health, behavioural and social scientists to discuss the interaction between biological, psychological, sociological, economic, ecological, and socio-economic factors that determine sedentary behaviour. Experts will be invited and in-depth multidisciplinary discussions will be held on; how these mechanisms change over the life course, how these factors and their interactions differ between social and ethnic groups and what are the right targets for actions at multiple levels. The objective of the meeting is to finalise a transdisciplinary consensus framework for research on determinants of sedentary behaviour across the life course. The workshop will follow an interactive Delphi process, and international speakers like Jo Salmon, John Reilly, Genevieve Healy, Dawn Skelton, Neville Owen and David Conroy will talk about determinants of sedentary behaviour throughout this workshop.
You can subscribe to this satellite meeting by clicking here.
Today’s post comes from friend and colleague Dr Stephanie Prince, discussing her important new paper published in Obesity Reviews (available free here). More on Stephanie can be found at the bottom of this post.
Physical activity has long been established as a strong predictor of cardiometabolic health, disease and mortality. For decades now researchers have been trying to develop interventions that will increase our physical activity levels, most notably at higher intensities – think moderate-to-vigorous physical activity (otherwise known as MVPA). In Canada, we have physical activity guidelines which promote that adults (18-64 years) aspire to achieve a minimum of 150 minutes of MVPA per week in bouts of 10 minutes or more, with the idea that more physical activity is always better. Canadians also have sedentary behaviour guidelines for children and youth which propose limits on screen time.
There is a rapidly growing body of literature which suggests that greater amounts of time spent being sedentary (watching TV, screen time, sitting time, total sedentary time) are associated with an increased risk for markers of cardiometabolic disease, cardiovascular disease, diabetes, some cancers and premature death (references here and here). Sedentary behaviours refer to the time spent sitting or lying down and in a state where there is relatively minimal energy expended (not just the absence of MVPA).
While there has been a lot of research looking at the effectiveness of physical activity interventions, little has been done to examine whether these interventions also decrease the time we spend being sedentary. Prior to this review I often wondered whether the opposite might occur whereby individuals who increased their physical activity levels may become more sedentary almost has a consequence of the satisfaction that they had already undertaken the necessary amount of physical activity needed to meet physical activity guidelines. Although in its infancy compared to the physical activity field, the sedentary behaviour field is now proposing and testing a variety of interventions targeting sedentary behaviours exclusively (with the majority to date having focused on office environments, where many of us spend the majority of ours days sitting at desks in front of computers). While the efficacy of physical activity interventions is more known, it remains unknown whether these intervention also have the capacity to decrease sedentary time. Further it is unknown whether interventions which target sedentary behaviours are any better at reducing these behaviours than physical activity interventions.
Therefore, the objective of our research was to systematically review the literature and compare the effectiveness of interventions with a focus on physical activity and/or sedentary behaviours (e.g.physical activity only interventions vs. physical activity + sedentary behaviour interventions vs. sedentary behaviour only interventions) for reducing time spent being sedentary in adults.
What did we do?
To examine all available literature we conducted a systematic review which searched six different bibliographic databases (you can see more details on this in the full article) looking for any study which described a physical activity and/or sedentary behaviour intervention and reported on changes in total sedentary time or time spent watching TV or sitting among adults. All of the studies included in the review can be found in the supplemental tables found here. We were also very fortunate to obtain several unpublished results provided to us upon request from authors of original studies where sedentary time was captured, but not reported upon in previous articles.
We assessed the quality and risk of bias of every individual study and also used the GRADE (Grading of Recommendations Assessment, Development and Evaluation) framework, essentially the gold standard for assessing the overall quality of the evidence and for rendering a recommendation based on the current evidence.
[Travis’ note: This was a lot of work!!!]
What did we find?
After we removed duplicate papers, we ended up retrieving 9,107 relevant papers. That was a lot of papers to screen! After many hours and days looking at the abstracts and then the full articles, 63 studies were kept in the review having met our inclusion criteria. Of these 63, 33 were used in the meta-analyses which allowed us to group quantitative results to yield an overall effect of the interventions. See Figure 1 for the PRISMA flow diagram to get a sense of how we screened out papers.
When we examined all of the evidence looking at both the more descriptive results of what the studies found and also at the quantitative results (see Figure 3 above) we found that on average the physical activity interventions resulted in significant, though very small reductions in sedentary time (average difference of 19 minutes/day). When interventions had both a physical activity and sedentary behaviour component they resulted in significant, but slightly greater reductions in sedentary time (average difference of 35 minutes/day) (Figure 4). Most promising is that when interventions focused solely on the behaviour itself, they yielded an average reduction of 91 minutes/day.
Today’s post comes from Juliet Harvey. You can find out more about Mrs Harvey at the bottom of this post. To submit your own post describing research of interest on sedentary behaviour, please contact email saunders dot travis at gmail dot com.
With recent studies suggesting a link between sedentary behaviour, health and well-being it is important to consider the sedentariness of older adults. Two recent systematic reviews have examined the levels of sedentary behaviour in older adults. Both papers took a global perspective and examined a range of measurement of sedentary behaviour reported by peer reviewed sources.
The first paper (Harvey et al., 2013) examined the prevalence of sedentary behaviour, where “cut-points” were used to give population prevalence of various levels and modes of sedentary behaviour. Almost 60% of older adult’s reported sitting for more than 4 h per day, 65% sat in front of a screen for more than 3 h daily and over 55% reported watching more than 2 h of TV. However, when measured objectively, in a small survey, it was found that 67% of the older population were sedentary for more than 8.5 h daily.
The second paper (Harvey et al., 2014) examined the average levels of sedentary behaviour reported by and measured in older adults. Objective measurement of SB, by accelerometry, shows that older adults spend an average of 9.4 hours daily sedentary in a waking day. Self-report of SB is lower at 5.3 hours daily, with 3.3 hours TV viewing reported.
As is seen in other studies, both papers found there were various methods employed to define and measures sedentary behaviour. There were vast difference between objective and subjective measurement of sedentary behaviour. These papers show that older adults do exhibit high levels of sedentary behaviour, which are similar to that of the adult population, despite the fact they may accumulate the sedentary time in different patterns.
About the author: Juliet Harvey is a physiotherapist and researcher in the Institute for Applied Health Research at Glasgow Caledonian University. Her research focuses on reducing sedentary behaviour in older adults. Juliet hopes to complete her PhD by summer 2015. Her contact details can be found here.
A 2 day conference on determinants of sedentary behaviour will be taking place on June 8 and 9th at Glasgow Caledonian University. A description and links for more details can be found below.
Reducing sedentary behaviour is a public health challenge internationally. Currently there is disparate and limited knowledge about its determinants across the life course to inform interventions. This meeting will bring together epidemiologist, psychologist, clinicians, economist, rehabilitation, life, health, behavioural and social scientists to define a consensus system approach model of the life course determinants of sedentary behaviour. The meeting will be held as part of the European Knowledge hub on Determinants of Diet and Physical Activity (www.dedipac.eu). During the meeting all attendees will be able to voice their opinion and watch consensus unfolding in real-time using the latest interactive information technology and consensus methodology. Key note speakers (Neville Owen, Jo Salmon, John Reilly, Genevieve Healy, Stef Kremers, Dawn Skelton and David Conroy) will chair the meeting. Registration includes an evening reception in which delegate will sample the finest Scottish Hospitality.
Dr. Morris Collen, a physician and pioneer of computerized medicine, passed away in September at the age of 100 years. The New York Times ran a story on his life given his significant contributions to computerzied medicine and noted Dr. Collen’s explanation for his productivity and longevity. In his 90s, Dr. Collen explained:
“I sit and write most of the day,” he said. “I set a kitchen timer for 60 minutes as soon as I sit down, and when that timer goes off, then I get up and walk up and down stairs and walk around the hallway for several minutes and go back and work on the book.”
Click here to read the story in full.
Subtracting sitting versus adding exercise on glycemic control and variability in sedentary office workers
A new study published in the journal of Applied Physiology, Nutrition and Metabolism examines the metabolic impact of adding exercise vs reducing sitting time.
The abstract, via the journal of Applied Physiology, Nutrition and Metabolism:
Recent evidence suggests that, like adding exercise, reducing sitting time may improve cardiometabolic health. There has not been a direct comparison of the 2 strategies with energy expenditure held constant. The purpose of this study was to compare fasting and postmeal glucose and insulin concentrations in response to a day with frequent breaks from sitting but no exercise versus considerable sitting plus moderate exercise. Ten sedentary overweight/obese office workers were tested in 3 conditions: (i) walking per activity guidelines (AGW): sitting for majority of workday with a 30 min pre-lunch walk; (ii) frequent long breaks (FLB): no structured exercise but frequent breaks from sitting during workday with energy expenditure matched to AGW; and (iii) frequent short breaks (FSB): number of breaks matched to FLB, but duration of breaks were shorter. Plasma glucose and insulin areas under the curve were measured in response to a meal tolerance test (MTT) at the end of the workday and interstitial glucose was evaluated throughout the day and overnight using continuous glucose monitoring. Using repeated-measures linear mixed models, area under the curve of plasma glucose or insulin after the MTT was not different between conditions. Glycemic variability was lower in FLB compared with AGW (p < 0.05), and nocturnal duration of elevated glucose (>7.8 mmol/L) was shorter after FLB (2.5 ± 2.5 min) than AGW (32.7 ± 16.4 min) or FSB (45.6 ± 29.6 min, p = 0.05). When energy expenditure was matched, breaks from sitting approximated the effects of moderate-intensity exercise on postmeal glucose and insulin responses and more effectively constrained glycemic variability.
The full text of the article can be found here.
Due to the increasing prevalence of childhood obesity, the association between classroom furniture and energy expenditure as well as physical activity was examined using a standing-desk intervention in three central-Texas elementary schools. Of the 480 students in the 24 classrooms randomly assigned to either a seated or stand-biased desk equipped classroom, 374 agreed to participate in a week-long data collection during the fall and spring semesters. Each participant’s data was collected using Sensewear® armbands and was comprised of measures of energy expenditure (EE) and step count. A hierarchical linear mixed effects model showed that children in seated desk classrooms had significantly lower (EE) and fewer steps during the standardized lecture time than children in stand-biased classrooms after adjusting for grade, race, and gender. The use of a standing desk showed a significant higher mean energy expenditure by 0.16 kcal/min (p < 0.0001) in the fall semester, and a higher EE by 0.08 kcal/min (p = 0.0092) in the spring semester.
The full text article is available for free here.
A recent story in the New York Times, “Steve Jobs Was a Low-Tech Parent,” discusses tech CEOs — including the late Steve Jobs — who understand the importance of limiting screen time.
From the story:
When Steve Jobs was running Apple, he was known to call journalists to either pat them on the back for a recent article or, more often than not, explain how they got it wrong. I was on the receiving end of a few of those calls. But nothing shocked me more than something Mr. Jobs said to me in late 2010 after he had finished chewing me out for something I had written about an iPad shortcoming.
“So, your kids must love the iPad?” I asked Mr. Jobs, trying to change the subject. The company’s first tablet was just hitting the shelves. “They haven’t used it,” he told me. “We limit how much technology our kids use at home.”
Click here to read the story in full for free.