Physical Activity Appears to Reduce Mortality Risk, But Not In Those Who Are Obese, Study Shows

TAMPA, Fla. -- A University at Buffalo study on the relationship between physical activity and mortality provides new evidence that life as a couch potato may bring an early death.

Results showed that physically active men who were not obese had a 60 percent lower risk of dying from heart disease, and a 41 percent lower risk of dying from any cause, than sedentary men.

Body weight appeared to be an important variable. The researchers found that overweight or obese men who were as active as their slimmer colleagues received no protective effect.

The project is the first to study a random sample of a general population and its total physical activity during work and leisure and its mortality statistics.

Results of the research, conducted by a team headed by Joan Dorn, Ph.D., research instructor in the UB Department of Social and Preventive Medicine, appeared in the February issue of Circulation and were presented here today (Friday, March 18) at the American Heart Association’s Epidemiology Council Conference.

The goal of the study was to determine if physically active men were less likely to die of heart disease in particular, and live longer in general, than men who took part in little physical activity.

The benefits of exercise, per se, have been documented previously. The UB study calculated the effect of a person’s normal physical routine on longevity and mortality, rather than focusing on specific activities such as walking, climbing stairs, doing yardwork or playing sports.

The study participants were interviewed originally in 1960, after being selected randomly from the general population of Buffalo to take part in an epidemiologic study. The original sample was composed of 866 men between the ages of 15 and 96. The researchers were able to follow up on 632 of the men, at an average interval of 29 years after the initial interview.

Within the follow-up group, 270 had died, 97 from coronary heart disease.

During the original interview, the men provided complete medical histories and details of their lifestyles, including a description of their work and leisure physical activity. Participants reported the number of work-day hours spent sitting at a desk, machine, car, bus, train or other vehicle; driving a vehicle; standing; carrying or lifting heavy things; shoveling or digging; other work activities they considered exercise; sleeping; and walking. The specific types of machines or vehicles used, objects lifted, etc, also were described.

Weekend physical activities included the number of hours usually spent in activities such as sitting, lying down, sleeping, standing at a machine, playing sports, other kinds of exercise, such as gardening or washing the car, and walking. Types of machines, sports and other exercise were probed in detail.

Results showed that higher levels of activity were associated with a 41 percent lower risk of death from any cause, and a 60 percent lower risk of death from heart disease in men who were not obese.

No such relationship was found in overweight and obese men, implying that a high body weight may nullify any beneficial effects of physical activity, researchers concluded. Similar trends were seen in men 65-and over, who were studied separately.

"A sedentary lifestyle is a habit we can change to help prolong our lives," said Dorn. "Contrary to other lifestyle changes that often mean giving up enjoyable habits, increasing your level of activity represents a pleasant way to lower the risk of early death."

Additional members of the research team were Maurizio Trevisan, M.D.; John P. Naughton, M.D.; John E. Vena, Ph.D., and Frank J. Cerny, Ph.D., all from UB, and Warren Winkelstein, M.D., from the University of California at Berkeley.