Even small amounts of physical activity will help reduce heart disease risk, and the benefit increases as the amount of activity increases, according to a quantitative review reported in Circulation, journal of the American Heart Association.

People who engaged in 150 minutes of moderate-intensity leisure activity had a 14 percent lower risk of coronary heart disease (CHD) compared to those who reported no exercise or physical activity. At higher levels of activity, the relative risk of CHD was progressively lower. Researchers found that even people who got below the United States guidelines for physical activity, which recommends 2 hours and 30 minutes of moderate exercise per week, had a lower risk of CHD than those who had no activity.

"The overall findings of the study corroborate federal guidelines - even a little bit of exercise is good, but more is better ? 150 minutes of exercise per week is beneficial, 300 minutes per week will give even more benefits," said Jacob Sattelmair, Sc.D., of the Department of Epidemiology at the Harvard School of Public Health.

Sattelmair said this work differs from previous reviews of studies examining physical activity and heart disease risk because it included quantitative assessments of the amount of physical activity a person may need to reduce their risk as well as the magnitude of benefit. In a meta-analysis, researchers examined more than 3,000 studies of physical activity and heart disease, and included 33 of them in their analysis. Among those, nine measured leisure activity quantitatively.

"Early studies broke people into groups such as active and sedentary. More recent studies have begun to assess the actual amount of physical activity people are getting and how that relates to their risk of heart disease."

The study also notes a significant interaction by gender, as these results were stronger in women than in men.