Too little exercise and too much sitting: Inactivity physiology and the need for new recommendations on sedentary behavior

Abstract

Moderate-to vigorous-intensity physical activity has an established preventive role in cardiovascular disease, type 2 diabetes, obesity, and some cancers. However, recent epidemiologic evidence suggests that sitting time has deleterious cardiovascular and metabolic effects that are independent of whether adults meet physical activity guidelines. Evidence from "inactivity physiology" laboratory studies has identified unique mechanisms that are distinct from the biologic bases of exercising. Opportunities for sedentary behaviors are ubiquitous and are likely to increase with further innovations in technologies. We present a compelling selection of emerging evidence on the deleterious effects of sedentary behavior, as it is underpinned by the unique physiology of inactivity. It is time to consider excessive sitting a serious health hazard, with the potential for ultimately giving consideration to the inclusion of too much sitting (or too few breaks from sitting) in physical activity and health guidelines.

Managing Sedentary Behavior to Reduce the Risk of Diabetes and Cardiovascular Disease

“…Pioneering animal experimental work [57][58][59] has demonstrated that when compared to exercise training, prolonged periods of muscle unloading (sitting) reduce glucose uptake and elicit a greater and muscle-specific (mostly in oxidative fibres) lowering effect on lipoprotein lipase regulation (a key protein for controlling plasma triglyceride catabolism, HDL cholesterol, and other cardiometabolic risk factors). These initial findings stimulated the hypothesis that prolonged sedentary behaviours may engage molecular signalling pathways distinct from lack of MVPA, rather than the behaviours associated with them.…”

Associations between time spent in green areas and physical activity among late middle-aged adults

“…With increasing life expectancy and an expected increased number of middle-aged (45 to 65 years) and older adults (≥65 years) in the future, health care costs are expected to rise globally (Department of Health, 2004;OECD, 2006). Sufficient physical activity and limited sedentary behaviour can prevent certain diseases, especially in middle-aged and older adults, who are more susceptible to cardiovascular diseases than younger people (Warburton et al, 2006;Cavill et al, 2008; US Department of Health and Human Services, 2008;King and Guralnik, 2010;Warburton et al, 2006;Hamilton et al, 2012).…”

Sitting-Time, Physical Activity, and Depressive Symptoms in Mid-Aged Women

“…6;6-14 Another lifestyle factor that may be important is sedentary behavior, which is typically defined as any waking activity characterized by an energy expenditure ≤ 1.5 metabolic equivalents and a sitting or reclining posture 15;16 , and is often conceptualized as sitting-time in epidemiological studies. 17 Although there is increasing evidence suggesting that sitting-time is associated with poor cardiovascular and metabolic health outcomes [18][19][20] and decreased life expectancy, 21;22 less is known about the association between sitting-time and psychological outcomes such as depression. 23 Cross-sectional studies show an inverse association between sedentary time and mental health in older adults, 24;25 disadvantaged women, 26 and overweight and obese adults.…”