Sitting has become the status quo. Whether that’s in a car, at a desk, or relaxing at home – we are constantly sitting.
During the last few decades, major societal changes affecting the industry and service sectors have led to an increase in sedentary lifestyles. As a result the prevalence of excessive sitting in most western countries is very high (A), especially in older adults (B). Why should you care? Because the amount of time spent sitting is associated with chronic diseases and poor quality of life, independent of physical activity (C). This means that even though you exercise for an hour a day, it may not make a difference.
Sitting may be harmful because of the prolonged absence of muscle contractile activity in the legs. It has also shown to produce alterations in metabolic risk factors (e.g., reduced insulin sensitivity and lower HDL). Furthermore, it is linked to mitochondrial dysfunction, increased exposure to reactive oxygen species, and increased inflammation in older adults, which may lead to accelerated cellular death (G). One recent study found that women with standing/walking occupations had lower risk of dying from all-causes and cancer (by 32% and 40%, respectively), relative to women with sitting occupations, after adjusting for multiple covariates (E).
Office jobs aren’t the only problem. Indeed, one meta-analysis showed that television viewing, which is the most studied type of leisure-time sedentary behavior, is significantly associated with an increased risk of type 2 diabetes, cardiovascular disease, and all-cause mortality (D). Television viewing is often done while snacking and/or consuming of soda, therefore a possible explanation for this association could be a difference in energy intake during television viewing. However, the associations between television viewing and mortality were adjusted for total caloric intake and didn’t change after adjustment for snacking and consumption of sugar‐sweetened beverages.
The American guidelines for adult exercise recommend doing at least 150 minutes of moderate-intensity exercise or 75 minutes of intense exercise per week, preferably spread throughout the week. For additional benefits, it recommends that the above guides should be doubled. These guidelines also recommend muscle-strengthening activities two or more days a week (F). However, this may not be enough to reduce the risk of disease and illness. Population-based studies have found that more than half of the average person’s day involves sedentary activities. For example, a person who reaches the recommended activity may be highly sedentary for up to 10 hours during the day. Recent findings suggest that, when adjusted for physical activity, sedentary time was independently associated with a greater risk for all-cause mortality, cardiovascular disease, cancer incidence, and type 2 diabetes in adults (H). However, these outcomes were less pronounced as participation in physical activity increased.
Some say that sitting is the new smoking. I don’t know if there is enough evidence to make that comparison, but recent studies indicate that it isn’t good for your health. Considering the average person works ~8 hours per day at a desk, the time for intervention is earlier rather than later. Hopefully over the next few years you’ll see an increase in standing/treadmill desks (though some companies are ahead of the curve). These aren’t cheap and will be hard to convince the boss to buy for the office, but until then you can start making small changes to improve your long-term health. You’re probably already exercising, so why not invest a few extra minutes standing at work each day.
Tips to reduce sitting:
A) Bauman A, Ainsworth BE, Sallis JF, et al.; IPS Group. The descriptive epidemiology of sitting. A 20-country comparison using the International Physical Activity Questionnaire (IPAQ). Am J Prev Med. 2011; 41: 228–35.
B) Matthews CE, Chen KY, Freedson PS, et al. Amount of time spent in sedentary behaviors in the United States, 2003–2004. Am J Epidemiol. 2008; 167: 875–81.
C) Balboa-Castillo T, León-Muñoz LM, Graciani A, Rodríguez-Artalejo F, Guallar-Castillón P. Longitudinal association of physical activity and sedentary behavior during leisure time with health-related quality of life in community-dwelling older adults. Health Qual Life Outcomes. 2011; 9: 47.
D) Grøntved A, Hu FB (2011) Television viewing and risk of type 2 diabetes, cardiovascular disease, and all-cause mortality: A meta-analysis. JAMA 305: 2448–2455. doi: 10.1001/jama.2011.812
E) Stamatakis, Emmanuel, Josephine Y. Chau, Zeljko Pedisic, Adrian Bauman, Rona Macniven, Ngaire Coombs, and Mark Hamer. “Are Sitting Occupations Associated with Increased All-Cause, Cancer, and Cardiovascular Disease Mortality Risk? A Pooled Analysis of Seven British Population Cohorts.” PloS One 8, no. 9 (2013): e73753. doi:10.1371/journal.pone.0073753.
G) Tremblay MS, Colley RC, Saunders TJ, Healy GN, Owen N. Physiological and health implications of a sedentary lifestyle. Appl Physiol Nutr Metab. 2010; 35: 725–40.
H) Biswas, Aviroop, Paul I. Oh, Guy E. Faulkner, Ravi R. Bajaj, Michael A. Silver, Marc S. Mitchell, and David A. Alter. “Sedentary Time and Its Association with Risk for Disease Incidence, Mortality, and Hospitalization in Adults: A Systematic Review and Meta-Analysis.” Annals of Internal Medicine 162, no. 2 (January 20, 2015): 123–32. doi:10.7326/M14-1651.