Run! No, walk. No, run!
The latest in a spate of seemingly conflicting studies says that to live longer, you must exercise vigorously, not just moderately.
Lately, many exercise advocates, including the government’s Centers for Disease Control and Prevention, have been pushing moderate activity.
But that won’t boost longevity, judging from 26 years of data on 17,321 healthy male Harvard alumni who graduated between 1924 and 1954, researchers report in today’s issue of The Journal of the American Medical Association.
“We found that only vigorous exercise was associated with lower mortality, and non-vigorous exercise did not at all reduce mortality rates,” said Dr. I-Min Lee, assistant professor of medicine at Harvard and lead author of the study.
Vigorous exercise was defined as any exertion that required at least six times as much energy as resting. That in cluded walking 4 to 5 mph, jogging, swimming laps, playing tennis or even doing heavy chores around the yard - if they truly were heavy chores, like building stone fences, and “not just puttering around,” Lee said.
The study did not spell out exactly how much of any specific activity would constitute vigorous exercise. But it said men who had the lowest risk of death burned at least 1,500 calories a week on vigorous activities. That’s equivalent to walking briskly 4 to 5 mph for at least 45 minutes a day, five days a week. Or, to jogging at least an hour three times a week, Lee said.
She hastened to add that moderate exercise has many other benefits - improving quality of life, promoting physical well-being, enhancing the ability of older people to accomplish daily tasks, regulating blood pressure and averting diabetes.
“I don’t want to dissuade couch potatoes from exercising,” Lee added Tuesday. “I strongly believe that any exercise is better than no exercise. But for persons who can exercise at a higher level, why not do that? Because our data indicate they might live longer than other people.”
In the study, the most active group of men had a 25 percent lower risk of dying over the 26 years than the least active men, Lee said. The difference in risk was calculated after adjusting for differences that might have affected risk - age, smoking habits, high blood pressure, diabetes and the early death of one’s parents.
A 25 percent reduction in death risk equals the difference in risk between a pack-a-day smoker and a nonsmoker, or between a person who is 20 percent overweight and a person of ideal weight, she said.
Harold W. Kohl III, an epidemiologist for the Cooper Institute for Aerobics Research in Dallas, said the study “fits in nicely with 40 years of research on physical activity and health. I think it’s a welldone paper.”
But Kohl said he is not entirely convinced that moderate activity doesn’t extend life, even though this particular study fails to show it.
“Moderate to one person is not moderate to another,” Kohl noted.
The CDC and the American College of Sports Medicine in February issued new recommendations emphasizing the benefits of even intermittent and moderate bouts activity in reducing the risk of heart disease and promoting health. Such activity includes climbing a few flights of stairs, gardening or playing with children.