Doing some exercise is better for the heart than doing nothing, but adults who kick their workout routines up a notch will fare even better. That's what Harvard doctors are saying in a review published in "Circulation," a journal of the American Heart Association.

"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, ScD., an author of the article from the Department of Epidemiology at the Harvard School of Public Health.

This study was a breakthrough in terms of research on physical activity and heart disease risk.

"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," Sattelmair said.

And good news for the ladies: the results of exercise were stronger in women than in men.

The Office of Women's Health in the Department of Health and Human Services recommends a variety of workout routines, but says that women can gain more benefits by doing at least five hours of moderate intensity exercise or two hours and 30 minutes of vigorous-intensity aerobic physical activity weekly.

According to the Centers for Disease Control and Prevention, inactivity is one of several risk factors that can lead to heart problems.  Other risk factors include obesity and high blood pressure.