Too Much Sitting and Cardio-Metabolic Risk: An Update of Epidemiological Evidence
- 848 Downloads
Sedentary behavior, as distinct from a lack of moderate-to-vigorous physical activity, is an emerging health risk behavior for the development of chronic diseases. Examples of sedentary behavior include sitting, watching television, using a computer, and driving a car. In this article, we define sedentary behavior; outline key concepts related to the physiology of sedentary behavior, review the recent evidence on the effects of prolonged sedentary behavior (or sitting) on the risk of cardio-metabolic disease and all cause mortality, and discuss the implications for current clinical practice. We found that most large scale studies on sedentary behavior were published in the last 5 years. There is moderately consistent evidence for an association between total sitting time and all-cause mortality, even when adjusted for or stratified by leisure time physical activity. Overall, we identified a compelling case for sitting reduction to be included in clinical preventive advice as a key component of ‘active living,’ where adults and children are encouraged to ‘move more and sit less’ across different settings and locations throughout the day.
KeywordsSedentary behavior Cardiovascular disease Diabetes Epidemiology
Compliance with Ethics Guidelines
Conflict of Interest
Adrian E Bauman declares that she has no conflict of interest. Josephine Y Chau declares that she has no conflict of interest. Ding Ding declares that he has no conflict of interest. Jason Bennie declares that he has no conflict of interest.
Human and Animal Rights and Informed Consent
This article does not contain any studies with human or animal subjects performed by any of the authors.
Papers of particular interest, published recently, have been highlighted as: • Of importance
- 1.• Lee IM, Shiroma EJ, Lobelo F, Puska P, Blair SN, Katzmarzyk PT. Effect of physical inactivity on major noncommunicable diseases worldwide: an analysis of burden of disease and life expectancy. Lancet. 2012;380:219–29. This paper was a recent summary of the epidemiological evidence for physical inactivity and health using a burden of disease approach. It is slightly outside the remit of ‘sitting and health’ research, but is an important recent distillation of the health impact of not being physically active, with an estimated 9% of premature mortality across the world attributed to physical inactivity ( not meeting moderate intensity physical activity recommendations). This is around 5 million deaths per year that could be prevented if physical inactivity were abolished, and is a similar attributable number for tobacco smoking globally, and substantially larger to that attributed to obesity. For this reason, physical inactivity remains an important and under-recognized issue in preventive health.PubMedCrossRefGoogle Scholar
- 2.WHO. Global recommendations on physical activity for health. Geneva: World Health Organization; 2010.Google Scholar
- 3.• Proper KI, Singh AS, van Mechelen W, Chinapaw MJM. Sedentary behaviors and health outcomes among adults: a systematic review of prospective studies. Am J Prev Med. 2011;40:174–82. This systematic review explored the relationship between sedentary behaviors and health outcomes in adults, and identified 19 studies. The evidence was mixed for some outcomes, but a moderate evidence for sitting behavior and diabetes was evident, and a strong relationship between sitting behavior and all cause and cardiovascular disease mortality was noted. This type of summary is starting to synthesize the evidence that enables us to move towards public health recommendations.PubMedCrossRefGoogle Scholar
- 6.• Katzmarzyk PT, Lee IM. Sedentary behavior and life expectancy in the USA: a cause-deleted life table analysis. BMJ Open. 2012;2:4. This meta-analysis reviewed studies of sitting and mortality, and estimated increased life expectancy amongst USA adults if sitting time was reduced. The authors estimated that life expectancy would increase by 2 years if sitting were reduced to less than 3 hours per day, and an increase of 1.38 years in life expectancy would accrue if television viewing was restricted to less than 2 hours per day. Whilst the former may be a difficult goal to achieve in sedentary workplaces, the latter is a population health goal that might be achievable if alternate ways of spending time in domestic setting, became culturally normative. This is a long term approach, but is an important idea in thinking about the beneficial effects of reducing sitting time.CrossRefGoogle Scholar
- 8.• Sedentary Behavior Research Network. Standardized use of the terms "sedentary" and "sedentary behaviors". Appl Physiol Nutr Metab. 2012;37:540–2. This methodological note describes the difference between not meeting physical activity recommendations (being inactive) and the specific sedentary behaviors, defined as “waking time behavior with an energy expenditure of less than 1.5 METS, whilst in a sitting or reclining position”. This definition is important because light physical activity might not meet recommendations, and includes standing or walking around, but is not classified as ‘sedentary behavior’ time. This distinction is important physiologically, epidemiologically, and for characterizing people’s lifestyle behaviors.CrossRefGoogle Scholar
- 10.Colley RC, Garriguet D, Janssen I, Craig CL, Clarke J, Tremblay MS. Physical activity of Canadian adults: accelerometer results from the 2007 to 2009 Canadian Health Measures Survey. Health Reports, Statistics Canada, Catalogue no. 82-003-XPE. 2011;22.Google Scholar
- 12.Aresu M, Bécares L, Brage S, Chaudhury M, Doyle-Francis M, Esliger D, et al. Health survey for England 2008 Volume 1. Physical activity and fitness. UK: the NHS Information Centre for health and social care, 2009.Google Scholar
- 25.• Dunstan DW, Kingwell BA, Larsen R, Healy GN, Cerin E, Hamilton MT, et al. Breaking up prolonged sitting reduces postprandial glucose and insulin responses. Diabetes Care. 2012;35:976–83. This experimental study examines physiological responses to sitting and compares a small number of mid aged adults in a randomized trial, with subjects allocated uninterrupted sitting, 2 minutes of light intensity every 20 minutes, and 2 minutes of moderate intensity every 20 minutes. This tests the question whether interrupting sitting with just standing or with moderate intensity activity improves physiological parameters. Objectively measured glucose uptake was examined, and the area under the curve was reduced in both the standing and moderate intensity categories compared with uninterrupted sitting. The insulin ‘area under the curve’ was similarly reduced in both intervention groups, suggesting post prandial responses to sitting are ameliorated by interrupting sitting time. This has implications for normalizing sitting related physiological responses.PubMedCrossRefGoogle Scholar
- 38.de Heer HD, Wilkinson AV, Strong LL, Bondy ML, Koehly LM. Sitting time and health outcomes among Mexican origin adults: obesity as a mediator. BMC Public Health. 2012;12.Google Scholar
- 40.Banks E, Lim L, Seubsman SA, Bain C, Sleigh A. Relationship of obesity to physical activity, domestic activities, and sedentary behaviors: cross-sectional findings from a national cohort of over 70,000 Thai adults. BMC Public Health. 2011;11.Google Scholar
- 42.Pavey TG, Peeters GG, Brown WJ. Sitting-time and 9-year all-cause mortality in older women. Br J Sports Med. 2012;10. Accesible on: 1136/bjsports-2012-091676.Google Scholar
- 47.Department of Health, Physical Activity, Health Improvement and Protection. Start active, stay active: a report on physical activity for health from the four home countries’ Chief Medical Officers. UK: Department of Health, 2011.Google Scholar
- 48.Garber CE, Blissmer B, Deschenes MR, Franklin BA, Lamonte MJ, Lee IM, et al. American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Med Sci Sports Exerc. 2011;43:1334–59.PubMedCrossRefGoogle Scholar