Regular exercise can help slim a flabby tummy. But did you know that keeping fit might also reduce the size of a dangerously enlarged heart?

A study published in the June 19 issue of the Journal of the American College of Cardiology found that aerobic exercise can help people with stable heart failure by turning an enlarged heart into a trimmer, more efficient organ for pumping blood.

Weightlifting, on the other hand, may not be helpful.

Heart failure generally occurs following a heart attack or after many years of high blood pressure. The damaged heart becomes enlarged and too weak to pump blood effectively. As a result, people with heart failure tire quickly and become short of breath when they’re physically active.

However, studies have shown that regular exercise can help reduce symptoms of heart failure.

The new study, performed by researchers at the University of Alberta in Edmonton, shows that aerobic exercise, including walking and bicycling, may be the most effective type of exercise for improving symptoms and reshaping the heart.

People in the study who lifted weights for exercise didn’t enjoy the same benefits. This may be because strength training can stress the heart rather than help it, said the study’s lead author, Mark J. Haykowsky, Ph.D.

The findings were based on a review of 14 different trials involving a total of 812 people with heart failure.

People with heart failure should discuss the pros and cons of exercise with a doctor before embarking on any new fitness program.

In addition, an editorial accompanying the study stressed that exercise is not a substitute for other heart failure treatments, such as dietary and other lifestyle changes, medications and medical devices that may help the heart to pump.