Getting even a little bit of exercise is better than getting none at all, and this may hold especially true for women, a new study shows.  

The U.S government guidelines recommend getting 150 minutes of exercise a week, and the study showed that even people who exercised less than that had a lower risk of coronary heart disease than those who did not exercise.

Of course, more exercise is even better for you: People who did 150 minutes of moderate exercise weekly had a 14 percent lower risk of developing coronary heart disease than those who did no exercise, the study said.

And those who did 300 minutes of exercise a week had 20 percent lower risk of developing coronary heart disease than those who did not exercise. At higher levels of activity, the risk became progressively lower.

The association between more exercise and greater health benefits was stronger in women than it was in men, the study said, though it was unclear as to why. It could be that women have an overall lower risk of developing coronary heart disease than men do, so factors other than exercise that are difficult to measure precisely, such as diet, contributed to this effect. [Heart Disease a Serious, Silent Problem in Women]

The study provides the first evidence supporting the 2008 Physical Activity Guidelines for Americans, issued by the U.S. Department of Health and Human Services, the researchers said.

Previous research had shown that physical activity is associated with a 20 percent to 30 percent lower risk of coronary heart disease; however, it was not known how much exercise was needed to lower risks by this amount.

The study researchers based their conclusions on 33 previously conducted studies of physical activity and heart disease.

About 17 million people in the United States had coronary heart disease in 2010, the researchers said.

The study was published today (Aug. 1) in the journal Circulation.