If you sit a lot, staying physically active for at least an hour a day may cancel out the increase in mortality rate associated with being sedentary, according to an analysis in the Lancet, which pooled data from 16 studies involving more than a million people.
Day after day of prolonged sitting increases the risk of a range of health problems, including cardiovascular disease and diabetes, as discussed in a recent Science Advisory from the American Heart Association in the journal Circulation. However, research has been inconsistent about whether, and how much, exercise counters these risks.
The Lancet analysis concluded that about 60 to 75 minutes a day of moderate activity, such as brisk walking, was sufficient to eliminate the risk of premature death associated with sitting for more than eight hours a day. Sedentary TV viewing for more than five hours a day may be an exception, however, in that physical activity was found to lessen, but not eliminate, the excess mortality risk.
Also see Sitting Not So Pretty.