TUESDAY, April 7 (HealthDay News) -- A regular program of moderate exercise will not harm people with heart failure and probably will benefit some of them, a new study has found.

That admittedly tepid conclusion comes from a major government-funded trial that enrolled 2,331 people with heart failure at 82 centers in the United States, Canada and France.

Some were started on a 36-session training program and advised to have regular sessions of aerobic-type exercise, such as walking on a treadmill for 25 or 30 minutes, five times a week. Others were told to stick to a usual-care regimen, which included a passing reference to exercise.

The hope was that regular exercise would reduce the incidence of death and hospitalization caused by heart failure, the progressive loss of the heart's ability to pump blood. Some 5 million Americans have been diagnosed with heart failure, and it is a leading cause of cardiac death and hospitalization.

After an average follow-up of 30 months, "our primary or first analysis did show a very modest reduction in the primary endpoints, but it did not achieve the nominal level of statistical significance," said Dr. Christopher M. O'Connor, professor of medicine at Duke University, director of the Duke Heart Center and lead author of a report on the trial in the Journal of the American Medical Association..

The incidence of death or cardiac hospitalization was 58 percent in the usual care group and 55 percent in the exercise group. There was a slightly lower incidence of deaths in the exercise group than among the others: 16 percent versus 17 percent.

"What you want is a large reduction and a highly significant result," O'Connor said. So the researchers decided to take a closer look at the data, adjusting for some apparently esoteric factors that O'Connor described as "highly prognostic predictors of the primary endpoint," such as the presence of the heartbeat abnormality called atrial fibrillation, ability to perform on a cardiopulmonary exercise test and the blood-pumping measure called left ventricular ejection fraction.

After that adjustment, the researchers found that exercise reduced the incidence of hospitalization by 11 percent and cardiovascular death or heart failure hospitalization by 15 percent.

But exercise had other benefits, O'Connor said. "Significantly more patients had an improvement on the quality-of-life scale with exercise training than those who did not exercise," he said. "Exercise training also improves physical fitness level to a modest degree. These people are able to walk further and exercise longer on a treadmill."

A separate analysis also showed a lower incidence of depression in the exercise group.

The overall analysis showed better survival for people who actually stuck to the recommended exercise regimen, O'Connor said. Overall, adherence decreased from an average of 95 minutes a week to 74 minutes a week after a year. But that result, which he said would be described in a future paper, cannot be relied on, because it might simply be that people who felt better overall were the more likely to exercise, he said.

All things considered, O'Connor said, "my belief, based on these results and when you look at the totality of information, is that an exercise prescription should be offered to patients with heart failure who meet our entry criteria."

And, at the very least, "we can say that we've shown in this study that exercise training is safe," he said. "There was no increase in mortality, in hip fractures and in falls in the exercise training group versus the control group."

The trial results could lead to a shift in advice given to people with heart failure, said Dr. Mariell Jessup, a professor of medicine at the University of Pennsylvania and a spokeswoman for the American Heart Association.

"For many years, people with heart failure were told they should not exercise," Jessup said. "In the modern era, we recognize the benefits for heart failure patients of having regular exercise. It improves their well-being and functional status and appears to be safe."

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