Physical activity may help extend survival for patients with heart failure, a new review suggests.

"Patients with heart failure should not be scared of exercise damaging them or killing them," said principal investigator Rod Taylor, director of the Exeter Clinical Trials Unit at the University of Exeter Medical School, in England.

"The message for heart failure patients is clear. Exercise is good for you, it will make you feel better, and it could potentially make you live longer," Taylor said in a European Society of Cardiology news release.

The findings stem from an analysis of 20 trials involving more than 4,000 people with heart failure. Overall, exercise was associated with an 18 percent lower risk of death from all causes and an 11 percent lower risk of hospitalization, compared to not exercising, the researchers said.

While they can't prove a direct cause-and-effect relationship between exercise and survival, the researchers said benefits were seen in both men and women and regardless of heart failure severity or age.

Heart failure means the heart no longer pumps efficiently enough to meet the body's demands. Symptoms include shortness of breath, fatigue and fluid buildup in the legs. There's no cure for the condition, which affects about 5.7 million people in the United States, according to the U.S. National Heart, Lung, and Blood Institute.

Taylor said exercise may benefit heart failure patients in several ways. It improves physical fitness, boosts oxygen supply to the heart, reduces the risk of abnormal heart rhythms that can cause sudden death, and improves circulation.

Taylor said he's not advising taking up marathon running.

"This is about increasing one's routine physical activity -- for example, walking for 20 to 30 minutes three times a week at an intensity that makes you feel a little bit breathless but not necessarily symptomatic," he said.

But talk to a doctor before starting an exercise program. "Discuss it with your cardiologist or GP with the belief that it's going to benefit you," Taylor added.

"Personalizing interventions and targeting resources is a hot topic in health care," Taylor said. "Our research shows that all patients with heart failure should be encouraged to exercise. Policymakers and clinicians should therefore not deny any heart failure patient the chance to participate in exercise rehabilitation on the basis that it will not work for them."

The findings were presented Monday in Florence, Italy, at the European Society of Cardiology's annual meeting on heart failure. Until published in a peer-reviewed medical journal, the findings should be considered preliminary.