January 19th, 2015
Intense Exercise Doesn’t Eliminate the Hazard of Intense Sitting
Researchers in Toronto scoured the literature to find studies that assessed the health effects of sedentary behavior adjusted for physical activity. They found 47 studies, including 13 that assessed all-cause mortality, 14 that assessed cardiovascular disease and diabetes, and 14 that assessed cancer. Sedentary behavior was defined as “waking behaviors characterized by little physical movement and low-energy expenditure,” including sitting and television watching.
Sedentary time was associated with a statistically significant independent increase in risk for all-cause, cardiovascular, and cancer mortality, as well as the incidence of cardiovascular disease, cancer, and type 2 diabetes. Increased sedentary time had the biggest effect on the risk for type 2 diabetes. The authors also reported that increased exercise blunted but did not completely eliminate the excess risk associated with sedentary behavior. Separating the effects of sedentary behavior and exercise is not just an academic distinction. The authors note that public health programs have mostly sought to encourage physical activity. “Health-promotion messaging advocating for a reduction in sedentary time is far less common and faces many challenges.”
In an accompanying editorial, Brigid Lynch and Neville Owen write that studies looking at sedentary behavior and exercise suffer from many shortcomings, but “the implications of these findings are far-reaching. Sedentary behavior is ubiquitous. Society is engineered, physically and socially, to be sitting-centric. In our workplaces, homes, common methods of transportation, and recreational venues, we are required or encouraged to sit. Now, mounting evidence shows that sedentary behavior contributes to all-cause, cardiovascular, and cancer death as well as the incidence of cardiovascular disease, cancer, and type 2 diabetes.”
Senior study author David Alter said that “exercising one hour per day should not give us the… peace of mind to remain seated for the remaining 23.” James Brown, a much earlier expert in the field, offered this succinct advice: Get Up Offa That Thing.