Three months of carefully controlled exercise sessions on treadmills or stationary bikes reduced the labored breathing called dyspnea that often afflicts people with moderate heart failure, says a report in tomorrow's issue of the Journal of the American College of Cardiology.
One purpose of the study was to show that people with heart failure can be helped by light exercise, even if their condition makes them feel shortness of breath during mild exertion, says Dr. Donna Mancini, an associate professor of medicine at Columbia-Presbyterian Medical Center in New York City.
Twenty-five patients were enlisted in the trial, and 17 of them agreed to do light exercise over the three-month period. The other eight attended classes on relaxation and guided imagery techniques, with no exercise training, to serve as a control group.
"We were able to show that in the training group there was less shortness of breath during exercise than before the training program, while in the control group there were no changes," Mancini says.
The exercise program concentrated on improving function of the muscles of the legs for a reason, she says. It has been thought that better breathing would come only from better heart muscle function, but the study shows that improving muscle function "can improve the symptoms of heart failure. Otherwise you could say that the reason they are less short of breath is that their respiratory muscles are also being trained," she explains.
While Mancini says the study indicates that "even a low level of exercise is beneficial in improving symptoms," she also warns that anyone with heart failure should approach exercise with caution and should start training only after talking with a physician.
"You should probably have an exercise prescription, x number of repetitions of y kinds of exercise," she says. "The duration and setting of a workout on a treadmill or stationary bicycle should be specified."
The benefits of exercise probably come from improvements in muscle metabolism that changes the activity of receptors that set off signals triggering shortness of breath, Mancini says. However, it's also possible the training just makes people feel better overall, so that the symptoms of breathlessness become less bothersome to them. Either way, she says, "exercise helps these people feel better."
It's possible that there was a psychological element in the improvement, says Dr. Stanley Rubin of the Greater Los Angeles Health Care System, who was asked to comment on the study by the American College of Cardiology. "The active group clearly had more health-care giver interaction than the placebo group," Rubin says. "Because the outcomes are modestly beneficial, it is difficult to know for certain that the observed effect is solely due to the physical conditioning."
Nevertheless, he says, "therapy directed to the physical conditioning of the heart failure patient may be beneficial in improvement of symptoms."
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