News Release

Fighting heart disease a few minutes at a time

Peer-Reviewed Publication

American Heart Association

DALLAS, Aug. 29, 2000 -- In a study that is the first of its kind, researchers show that several short sessions of exercise may be as beneficial as a single long one if the total amount of exercise is the same, according to researchers reporting in today's Circulation: Journal of the American Heart Association. A second report today finds that vigorous exercise is more beneficial than moderate levels for fighting heart disease. Both studies included participants in the Harvard Alumni Study.

"Physical activity does not have to be arduously long to be beneficial," says researcher Howard D. Sesso, Sc.D., of the department of epidemiology at the Harvard School of Public Health, where the study was conducted. "Short sessions lasting 15-minutes long appear to be helpful. This may provide some impetus for sedentary individuals to take up physical activity."

Researchers say that their study lends some support for the current Surgeon General's recommendations that allow for the accumulation of shorter sessions of physical activity, as opposed to requiring one longer continuous session. Sesso says no previous study has compared the association of duration of exercise episodes, apart from its contribution to total energy expenditure, with heart disease risk.

Questionnaires were sent to 7,307 men (average age 66 years) in 1988 and 1993. Subjects reported their health habits and medical history and estimated the frequency and duration of their sessions of physical activity each week. Their reports were classified according to maximum average duration per episode and controlled statistically for other factors that would affect heart disease risk such as smoking, hypertension, diabetes, early parental death, and alcohol consumption.

Results showed that when the total energy expended was similar, longer sessions of exercise had a similar effect on heart disease risk compared with shorter sessions. Further, men who engaged in sports or recreational activities showed similar risks of heart disease as those who only walked and climbed stairs, provided the total energy output was similar.

"The important thing, apparently, is just to do it," says Sesso. "If you are unable to set aside 30 minutes all at once for exercise, try two 15-minute sessions."

In the second study researchers sent questionnaires to 12,516 middle-aged men (average age 57 years) in 1977 and again in 1988 and 1993. These men were asked to report on their health and on how much energy they expended during a typical week in everyday activities such as climbing stairs, walking city blocks, and sports or recreational activities. Survey results were tabulated into five categories of energy expenditure and three categories of exercise intensity. Information was also collected on other risk factors that could affect heart disease risk, such as smoking, alcohol consumption, body mass index, hypertension and diabetes.

Researchers found that people who reported more intense physical activity had a lower risk of heart disease.

"We found a 10- 20 percent reduction of heart disease risk for people participating in greater amounts of vigorous exercise each week," says Sesso. "For those who reported walking three miles or more per week, which is a moderate level of exercise, we found a 10 percent reduction in risk."

In general, "vigorous" activities include running or jogging, swimming laps, tennis, or aerobics, while "moderate" activities included walking, yard work, golf or social dancing.

"The benefits of physical activity seem to be independent of other coronary factors," says Sesso. "You don't need to become an Olympic athlete to reap these benefits. Just push yourself a little and get your heart rate up."

Sesso and other members of the Harvard research team are currently working on studies that address how best to get results from moderate-intensity exercise. The Harvard Alumni Study is an ongoing study of men who were undergraduates at Harvard University between 1916 and 1950. It was initiated in 1962.

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Co-authors of the two studies include Ralph S. Paffenbarger, Jr., M.D., Dr.P.H.; and I-Min Lee, MBBS, Sc.D.

NR00-1169 (Circ./Sesso)

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