May be offset by 1 hour of exercise
At least an hour of brisk walking or other moderate-intensity activity each day can reverse that risk associated with sitting for a long period, i.e. more than 8 hours daily; or more than 3 hours of TV watching daily.
This was the suggestion of a recently published meta-analysis in Lancet’s physical activity series. Prolonged sitting has already been linked with an increased mortality risk in previous researches.
In this meta-analysis, 16 prospective cohort studies evaluating the cardiovascular-risk impact—specifically on mortality—of adult sitting or TV viewing time, were included. The suggestion was that sitting more than 8 hours daily was linked with a 27 percent increased mortality risk compared with sitting less than 4 hours daily. However, in individuals who had 60–75 minutes of activity daily — prolonged sitting was not linked with increased mortality.
An additional finding was that watching TV for more than 3 hours daily was also apparently associated with increased mortality in all except again, the most active group. However, even in the most active group, watching TV for 5 hours a day was also associated with a mortality increase. Ma. Vanessa L. Estinozo with Lancet and Journal Watch reports
Vital Signs August 2016