Physical Activity Attenuates the Association Between Prolonged Sitting and Excess Mortality

Sedentary behavior is associated with risk for premature death (NEJM JW Gen Med Sep 1 2012 and BMJ Open 2012; 2:e000828). In this meta-analysis of 16 prospective cohort studies, researchers examined the associations of sitting time and physical activity with all-cause mortality in more than 1 million healthy adults. Participants were assigned to quartiles of sitting time, television-viewing time, and physical activity; the group that sat the least (<4 hours daily) and was most active (>35.5 metabolic equivalent [MET]-hours weekly) served as the reference group. Follow-up ranged from 2 years to 18 years.

Compared with the reference group, all-cause mortality was 12% to 59% higher in the two lowest quartiles of physical activity; within each o…