(AP)
Updated: 2007-09-06 10:40

VIENNA, Austria -- Having a bad heart doesn't mean you can skip exercise, doctors said Wednesday. In fact, it may even help your heart to repair itself. Research presented at the European Society of Cardiology meeting showed that exercise sparks the creation of new heart vessels.

In a small study of 37 people at Leipzig University in Germany, Dr. Robert Hollriegel found that people with serious heart failure who rode a bike for up to 30 minutes a day for four months produced new stem cells in their bones.

They also had more small blood vessels in their muscles. Those who didn't exercise had no change in their vessels or muscles.

Most patients with heart failure are over 70 years old, and some can barely walk a few steps without stopping for rest. Doctors think that even these patients would benefit from light exercise such as walking or cycling. To ensure that patients will be able to handle a certain level of physical activity, doctors conduct a test first to determine their maximum limits and to ensure they would not be exceeded. Some exercise regimens also are supervised by health professionals.

"We're not talking about patients with acute heart problems," said Dr John Cleland, a heart failure specialist at the University of Hull in Britain who is spokesman for the European Society of Cardiology. Cleland was not involved in Hollriegel's research.

"This is to prevent people from getting into a cycle of deterioration where they're afraid to exercise and they just avoid any activity that leaves them out of breath," he said.

Physical activity strains the heart's arteries and muscles by sending 10 times the normal amount of blood to the muscles being used. Stem cells then are dispatched to relieve this stress and may repair any damaged parts. If you continue to exercise, these stem cells help the body adapt to the stress, by building new blood vessels and strengthening muscles. But to maintain such benefits, you must exercise regularly.

Cleland said that people with heart failure should exercise to a state where they're breathless at least once a day. Pushing the limits of their heart's capabilities should help make it stronger.

"People think that if they have heart failure, then they're at the end of the road and they can't exercise," said Dr Freek Verheugt, a cardiologist at the University of Nymegen in the Netherlands. "But this study shows that exercise can work to produce new blood vessels, even in patients with serious heart disease."

Because no drugs exist to produce new stem cells, exercise may be the only method for some patients to rebuild their hearts.

"We are not saying that patients should run marathons, but there is no other way to augment your arteries," said Dr Francois Carre of Rennes University Hospital in France. "Patients have to exercise if they want that."

Previous studies have shown that people who do physical therapy after a heart attack live longer than those who don't. Experimental studies in rats have also suggested that exercise can even be more effective than statins, drugs that are commonly used to treat heart disease.

Though doctors routinely recommend that patients exercise, it is not an actual treatment. Carre thinks that should change. "We need to write patients prescriptions to exercise the same way we write prescriptions for drugs," he said.

"People have been trying for years to create a polypill to treat many different parts of heart disease," Carre said. "But that already exists. It's exercise."