Diabetologia: Sedentary time in adults and the association with diabetes, cardiovascular disease and death: systematic review and meta-analysis
Aims/hypothesisSedentary (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.MethodsMedline, 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.ResultsEighteen 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/interpretationSedentary 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.
New Paper: Impact of “noncaloric” activity-related factors on the predisposition to obesity in children
The research related to childhood obesity generally emphasizes the impact of unhealthy eating and sedentary behavior as the main determinants of the predisposition to the positive energy balance that underlies excess body fat accumulation. Recent investigations have, however, demonstrated that “noncaloric” activity-related factors can induce a significant imbalance between spontaneous energy intake and energy expenditure. This is the case for short sleep duration that favors hormonal changes that increase hunger and energy intake. This agrees with our research experience demonstrating that short sleeping predicts the risk of obesity in children to a greater extent than sedentary behavior. Recent research by our team has also showed that demanding mental work promotes a substantial increase in energy intake without altering energy expenditure. In addition, our preliminary data suggest that the regular practice of school-related cognitive efforts is predictive of an increase in abdominal fat accumulation. As discussed in this paper, individual variations in brain oxygenation and its related cerebral aerobic fitness might play a role in the relationship between mental work, energy intake, and the risk of excess body weight.
The full paper is available for free here.
Earlier this year SBRN published a new definition of sedentary behaviour in in French and English in the journals Applied Physiology, Nutrition and Metabolism, Movement & Sport Sciences – Science & Motricité and the African Journal for Physical, Health Education, Recreation and Dance.
Although the APNM and AJPHERD versions have been online for a month or so, due to differences in publishing schedules the Movement & Sport Sciences issue was published online this past week. It can be found here.
Here is the definition of sedentary behaviour, as proposed by the SBRN membership:
We suggest that journals formally define sedentary behaviour as any waking behaviour characterized by an energy expenditure ≤1.5 METs while in a sitting or reclining posture. In contrast, we suggest that authors use the term “inactive” to describe those who are performing insufficient amounts of MVPA (i.e., not meeting specified physical activity guidelines).
Nous suggérons que les revues définissent de façon formelle le comportement sédentaire comme une situation d’éveil caractérisée par une dépense énergétique ≤1,5 METs en position assise ou allongée.En revanche, nous suggérons que les auteurs utilisent le terme « inactif » pour décrire les individus ayant un niveau insuffisant d’activité physique d’intensité modérée à intense (MVPA), c’est-à-dire, n’atteignant pas le seuil d’activité physique recommandé.
The definition can be cited as:
From BMJ Open:
Objectives To determine the impact of sitting and television viewing on life expectancy in the USA.
Design Prevalence-based cause-deleted life table analysis.
Setting Summary RRs of all-cause mortality associated with sitting and television viewing were obtained from a meta-analysis of available prospective cohort studies. Prevalences of sitting and television viewing were obtained from the US National Health and Nutrition Examination Survey.
Primary outcome measure Life expectancy at birth.
Results The estimated gains in life expectancy in the US population were 2.00 years for reducing excessive sitting to <3 h/day and a gain of 1.38 years from reducing excessive television viewing to <2 h/day. The lower and upper limits from a sensitivity analysis that involved simultaneously varying the estimates of RR (using the upper and lower bounds of the 95% CI) and the prevalence of television viewing (±20%) were 1.39 and 2.69 years for sitting and 0.48 and 2.51 years for television viewing, respectively.
Conclusion Reducing sedentary behaviours such as sitting and television viewing may have the potential to increase life expectancy in the USA.
The full article is available for free here.
As with previous meetups at ICDAM and ISBNPA, SBRN recently hosted an informal meetup at the American College of Sports Medicine Annual Scientific Meeting in San Francisco, USA. The lunch was organized by Ernesto Ramirez, and was attended by 14 researchers from Europe, North America, and Oceania.
The conference also featured numerous well-received presentations by SBRN members. One such presentation by Bethany Howard of the Baker IDI is shown below.
If you are heading to a conference and would like to organize a meetup for other sedentary behaviour researchers under the SBRN banner, please go right ahead! Feel free to send a note to the list serve organizing the event, and you’re good to go. We love to highlight the events here on the website, so please try to get a picture if you can.
A lot has happened in the past few months and we thought this would be an excellent time for another quick SBRN update.
1. Sedentary behaviour definition letter published in 4 journals
Since our last update, the SBRN letter updating the definition of sedentary behaviour has been accepted/published in 2 additional journals:
Mental Health and Physical Activity and the African Journal for Physical, Health Education, Recreation & Dance.
As mentioned previously, the letter has also been published in Applied Physiology, Nutrition and Metabolism and Movement & Sport Sciences – Science & Motricité.
Thanks to everyone who contributed to the letter! Please cite the article in your own work, and refer people to it when you are acting as a reviewer.
The citation for APNM is:
Sedentary Behaviour Research Network. 2012. Standardized use of the terms “sedentary” and “sedentary behaviours”. Appl Physiol Nutr Metab. 37: 540–542.
2. Informal SBRN Meetings at ICDAM, ISBNPA & ACSM
The British Heart Foundation National Centre has just released an evidence briefing focused on sedentary behaviour. From their website:
The benefits of a physically active lifestyle are well established and reflected in public health guidelines and policy. In recent years there has been growing interest in the role that sedentary behaviour may play in health and wellbeing.
Informed by this emerging body of evidence, public health guidelines now recommend that people of all ages should avoid prolonged periods of sedentary behaviour and break up periods of sitting.
This new BHFNC evidence briefing provides an overview of the evidence relating to sedentary behaviour and public health.
It defines sedentary behaviour and summarises the risks and current levels as well as the implications for policy and practice. It also reviews the evidence for the effectiveness of interventions to reduce sedentary behaviour.
The full report can be downloaded for free here.
Adding to the success of the SBRN meeting at ICDAM in Rome, Dori Rosenberg organized another SBRN meetup at ISBNPA this past week in Austin, Texas. From the picture above it looks like there were at least 11 members in attendance, and all reports are that it was a very successful meeting. Thanks to Dori for organizing the meetup, and to Dr Stuart Biddle for providing the above photo.
If you are planning on attending a meeting that you think will be of interest to other SBRN members, please feel free to organize your own meetup under the SBRN banner! One of the main reasons for the creation of SBRN was to help sedentary behaviour researchers connect with each other, so the more “real world” meetups the better!
Finally, don’t forget that we’ll be having another meeting at ACSM in San Francisco on May 31 at 11:30. Details here.
The Sedentary Behaviour Research Network recently had it’s first “real-world” meetup at the International Conference on Diet and Activity Methods in Rome, Italy. The event was attended by SBRN members from Canada, Australia, and Great Britain. Thanks to Rachel Colley for organizing the event and to everyone who participated in Rome.
This Thursday (May 31) SBRN will be hosting another meetup at the American College of Sports Medicine conference in San Francisco, USA. It will be taking place from 11:30 to 1:30 at The Chieftan Pub & Grill, which is within walking distance of the conference site.
So far 14 SBRN-members from the USA, Australia and Canada have RSVP’d for the event at ACSM. If you’d like to join us, please add your name here so that we can ensure that we reserve enough seats. Huge thanks to SBRN member Ernesto Ramirez for taking the lead on organizing this meetup.
If you are interested in creating a similar meetup at any upcoming conferences, please feel free to do so! Just send an email to the SBRN list-serve to let people know when and where you’d like to meet.
Looking forward to seeing everyone at ACSM!
From Medicine and Science in Sports and Exercise:
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−1 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.
The full article is available via the MSSE website.