Current guidelines recommend physical activity of approximately 2.5 hours per week for improved health. These US researchers quantified the cardiovascular risk reduction of specific amounts of physical activity using a meta-analysis of prospective cohort studies. Thirty three studies met inclusion criteria. They used random-effects generalized least squares spline models to calculate dose-response estimates.
The researchers found: "Individuals who engaged in the equivalent of 150 min/wk of moderate-intensity leisure-time physical activity (minimum amount, 2008 US federal guidelines) had a 14% lower coronary heart disease risk (relative risk, 0.86) compared with those reporting no leisure-time physical activity. Those engaging in the equivalent of 300 min/wk of moderate- intensity leisure-time physical activity (2008 US federal guidelines for additional benefits) had a 20% (relative risk, 0.80) lower risk. At higher levels of physical activity, relative risks were modestly lower. People who were physically active at levels lower than the minimum recommended amount also had significantly lower risk of coronary heart disease. There was a significant interaction by sex. The association was stronger among women than men."
The researchers concluded: "These findings provide quantitative data supporting US physical activity guidelines that stipulate that 'some physical activity is better than none' and 'additional benefits occur with more physical activity.'"
Circulation 124(7):789-795, 16 August 2011