After Heart Attack, More Exercise Not Always Better
Excessive walking, running may lose protective effect
The study did find that the heart benefits of walking compared to running were equivalent, as long as the energy output was the same -- walking will take about twice as long as running to burn the same number of calories.
The study is published online Aug. 12 in Mayo Clinic Proceedings.
In the same issue, Spanish researchers reviewed the findings of 10 published studies, looking at the effect of elite athletes' training on longevity.
That study included more than 42,000 athletes, mostly men, who had participated in football, baseball, track and field, and cycling. Elite athletes lived longer than the general population, the study found. This suggests that health effects of exercise, especially for reducing heart disease and cancer risk, are not always confined to moderate doses.
That finding isn't necessarily at odds with the other study, said Lavie, co-author of an editorial accompanying the studies.
"It's at least comforting to know that previously athletic, high-competition, high-level athletic activity does not seem to be associated with worsening of survival," but actually with benefits of survival, he said.
Also, the exercise done by the athletes was often not at the extreme level of marathoners, he said.
This is right in line with what heart doctors have recommended all along, said Dr. James O'Keefe, another editorial co-author and a cardiologist at St. Luke's Mid-America Heart Institute in Kansas City, Mo. "Exercise is the best thing you can do for your health," he said, if done in moderation.
"It's not good to be sedentary, but you can overdo it," he said.
Half of the U.S. population gets too little exercise, O'Keefe estimated, and "maybe one in 20 is getting too much."
According to O'Keefe, if you are exercising mostly for health (not fitness) benefits, 2.5 to 5 hours of vigorous exercise a week is plenty. He and his colleagues also noted that taking one or two days off from high-intensity exercise each week might pay off as well.