Moderate Exercise Found to Reduce Risk of Disease
Even moderate exercise--such as a brisk walk each day--can significantly reduce a person’s risk of death from heart disease, cancer and other causes, according to new research that some say may help redefine the amount of activity prescribed to improve one’s health.
The study, published today in The Journal of the American Medical Assn., found that men even at relatively low levels of fitness were less than half as likely to die during the eight-year period studied than men who were sedentary.
Women, too, appeared to benefit dramatically: Inactive women were nearly twice as likely to die during the study period than women who got moderate exercise. A sedentary woman’s risk of death was more than four times greater than that of a truly fit woman.
“You don’t have to be an Olympic champion, you don’t have to be a marathon runner . . . to get a lot of benefit,” said Steven N. Blair, who headed the study. “Moderate fitness levels are associated with really quite strikingly reduced risk of death.”
Moderate fitness can be achieved by a brisk 30- to 45-minute walk each day, Blair said.
Experts in the field said the findings should serve as an impetus for the estimated 60% of all Americans who get no regular exercise. They should also make it easier for preventive medicine specialists to persuade inactive Americans of the benefits of activity.
“This is saying: Being active makes you healthy, reduces your disease risk and will very likely improve your longevity a little bit,” said Carl J. Casperson, a physical activity epidemiologist with the U.S. Centers for Disease Control.
While not startling, the findings are significant, researchers said, in that they are based on the most comprehensive study of its kind. And, the study links the health benefits of exercise not only to heart disease but to cancer and other causes of death.
Furthermore, the researchers were able to rule out smoking, high cholesterol levels and other factors as explanations for the difference in death rates. Taking those factors into account, the reduction in death risk still proved significant.
“We felt that we would see a significant decrease in deaths from cardiovascular disease, heart attack and other cardiovascular-related diseases,” said Dr. Larry W. Gibbons, a co-author of the study. “But we were a little bit surprised that the significant benefit came with only moderate fitness, and that it included a decrease in cancer rates.”
Just 7.5% of American adults get regular exercise--three times a week, for 20 minutes or more each time, at 60% of their capacity, according to federal data. Another 34% report engaging in some sort of less strenuous physical activity three times a week.
In recent years, health officials have urged Americans to improve or protect their health through exercise. But for the most part, they have urged a regimen of vigorous exercise such as sustained jogging, aerobic dance or swimming.
Blair, the director of epidemiology at the Institute for Aerobics Research, a private institute in Dallas, predicted that that advice will begin to change. In the future, he said, health officials will shift to encouraging more moderate, but achievable, levels of activity.
Blair’s group studied 13,344 men and women who received a preventive medical examination at the Cooper Clinic in Dallas between 1970 and 1981. Each person was tested for physical fitness and assigned to one of five categories ranging from unfit to highly fit.
The researchers then followed the participants for an average of eight years. During the study period, 283 died.
Among the men, 75 of those in the least fit category have died. Only 40 in the next category--just slightly more fit--have died. Similarly, 18 women in the least fit group have died, compared to just 11 in the next category.
Taking into account the varying numbers of people in each group, and calculating age-adjusted rates of death, the researchers concluded that the least fit men were more than twice as likely to have died than the men in the next, minimally fit, group.
The findings were similar for women.
“If you come from the lowest level of fitness and become slightly more fit, you will reduce your total disease burden,” said Casperson of the disease control center. “They’re saying this is the group that seems to need it most and it will not take much to get some protection.”
The difference between being inactive and being just slightly active was by far the most dramatic. The benefits of exercise continued to rise with each increased level of activity, but not at such a striking rate.
The researchers also found that fit people with high cholesterol levels were less likely to die than unfit people with low cholesterol levels. Similarly, fit people with high blood pressure were better off than unfit people with normal blood pressure.
“Fitness appears to overcome many of the harmful effects of cholesterol--many but not all,” said co-author Gibbons. “Individuals who were fit who had high cholesterol levels were still at much greater risk than individuals who were fit with low cholesterol levels.”
The Institute for Aerobics Research is a research institute devoted to the study of the relationship of exercise, nutrition and other forms of preventive medicine to overall health. It is affiliated with the Cooper Clinic, a preventive medicine clinic, and receives funding from private organizations and foundations as well as the federal government.
