It may not up longevity, but workouts will boost life-long health
The medical community has for decades trumpeted the message that even moderate amounts of exercise pay big returns on health. The importance of cutting back on dietary fat has been repeatedly advised as well. Yet, according to a recent study, the average body weight of Americans rose 8 pounds between 1980 and 1991, and a third of all adult Americans are now seriously overweight. That was an increase in the obesity rate of adult Americans of 8 percent in just 11 years.
Amidst this weight gain, exercise participation in several important demographic groups has dropped. Over 58 percent of all adults reported irregular or no leisure time physical activity in a 1991 federal government study. 
An analysis by the federal Centers for Disease Control and Prevention shows that the pattern is established for many by the time they reach high school.
Don't be one of those statistics. One recent study suggests that women who exercise an average of four hours a week have nearly a 60 percent lower risk of breast cancer, and that even one to three hours of exercise a week cuts a woman's risk by approximately 30 percent. Other research has found that regular exercise helps protect women against a variety of other diseases, including diabetes, heart disease, hypertension, and osteoporosis.
Upping the level of exercise intensity should not only benefit physical and emotional health but also may increase one's likely longevity. In the latest installment of a long-running study of Harvard men in middle age, researchers found that men who reported burning at least 1,500 calories in vigorous exercise each week had a 25 percent lower death rate on average than those whose exercise consumed no more than 150 calories a week. To reach the exercise levels measured in the Harvard study, a person would have to do one or a blend of the following each week: walk at 4 to 5 mph for 45 minutes five times; jog at 6 to 7 mph for 3 hours; play 1 hour of singles tennis three times; swim laps for 3 hours; cycle for 1 hour four times; rollerblade for 21/2 hours.
By the way, don't expect to improve your odds of living longer if you slack off your workouts. Previous research on the Harvard group showed that death rates were higher for former varsity athletes who sat out exercise in later life than for bookish grads who began or kept up exercise programs after they left college, whatever their athletic prowess.
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