The association of even minimal physical activity with reduced risk could be explained as an indicator of good habits in general, he said. "It is possible that they have a healthier lifestyle in general," Kenchaiah said.
The study found that doctors who rarely or never exercised were older, smoked cigarettes more often, and were more likely to have high blood pressure or diabetes.
"This new report reinforces what we've said in the past," said Dr. Gerald Fletcher, a preventive cardiologist at the Mayo Clinic in Jacksonville, Fla. "Not being obese but being overweight is definitely a risk factor for heart failure."
While Fletcher said he would have liked a more definitive indicator of physical activity -- the report described it as simply breaking a sweat -- he said the study showed again that "vigorous exercise makes the difference. The more you do, the better it is for you."
Two-thirds of Americans have excess body weight, and only about 30 percent exercise regularly, Kenchaiah said. About 660,000 new cases of heart failure are diagnosed each year in the United States, he said, and 80 percent of the men and 75 percent of the women aged 65 and older who are diagnosed with heart failure die within eight years.
Heart failure and its treatment are described by the American Heart Association.
SOURCES: Satish Kenchaiah, M.D., U.S. National Heart, Lung, and Blood Institute, Bethesda, Md.; Gerald Fletcher, M.D., preventive cardiologist, Mayo Clinic, Jacksonville, Fla.; Dec. 23, 2008, Circulation
All rights reserved