A new study shows that women can reduce their chances of developing heart disease by jogging for about three hours every week. The researchers at Harvard Medical School in Bostonhave just reported the results of the study on the New England Journal of Medicine. The study is the first to show the effectiveness of jogging in the developing of heart disease in women. Only a few earlier studies have examined the effects of jogging on the heart, but nearly all have been done on men. The new study involves more than 72,000 women between the ages of forty and sixty-five during a period of eight years. The researchers have found that women who jog at least three hours a week have a thirty to forty percent lower chance of suffering a heart attack than those who do not.