Physical Exercise and Health, 5: Sedentary Time, Independent of Health-Related Physical Activity, as a Risk Factor for Adverse Physical Health and Mental Health Outcomes.

Medical and neuropsychiatric benefits associated with physical exercise and activity are well recognized. It is less well known that time spent in sedentary behaviors, such as television-viewing or sitting at a desk, are associated with adverse health outcomes even after taking into consideration health-related physical activity. Although sedentary behaviors have become common in daily life, people tend to substantially underestimate how sedentary they actually are. The average person spends nearly 10 hours per day in a sedentary state, during leisure activities or work; sedentariness is even greater in persons with major mental illness such as psychosis. This article explains what sedentariness is, why sedentary behaviors are common in daily life, and how sedentariness is defined and assessed. Sedentariness is an important concept in its own right; it is not merely an absence of health-related physical activity. Sedentariness is associated with adverse outcomes in children and adolescents, adults, and older adults. Examples are provided of associations between sedentariness and adverse medical outcomes such as the metabolic syndrome, cardiovascular disease, stroke, and all cause mortality. Examples are also provided of associations between sedentariness and adverse mental health outcomes such as anxiety, depression, and dementia. Importantly, the adverse associations are independent of health-related physical activity; however, higher levels of physical activity may attenuate or offset the adverse effects of sedentariness. It is hoped that this article will encourage readers to reduce sedentary behaviors with a view to improve long-term physical and mental health.