Can You Overdose on Exercise?

Sweat does a body good, but is it easy to overdo it? One expert ways in. 

October 23, 2015
woman tired post-workout

Some researchers and writers would have you think so. They claim that running multiple marathons in your lifetime or competing in annual Ironman triathlons is bad for your health, raising your risk for heart attack, stroke, and possibly even cancer. With 32 marathons and 12 Ironman triathlons under my belt, I guess I am fast approaching the “finish line of life,” as one editorial on extreme exercise puts it. Do I think I should cut way back on exercise? No. Should I cross next year’s Ironman Lake Placid off my calendar? I don’t think so. 

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You might wonder if my personal interest has influenced my disregard for these extreme-exercise warnings, like the kid who plugs his ears and spouts loud nothings to avoid hearing his mother’s stern reprimand. And I get that. I love endurance exercise and want to keep doing it. But as a physician, I look at the best science and follow the strongest evidence. 

These recent studies claiming that loads of endurance exercise will harm your health and shorten your life are small and conflicting. There aren’t any big studies showing that marathoners and triathletes are dying young or that longevity declines as the amount of exercise increases. But there is significant evidence that the more physically active you are, the healthier you are and the longer you will live. In Sweden, a review of the medical records of nearly 50,000 men and women who compete in Nordic skiing races of up to 55 miles found that those who completed more races had lowered their risk of death.

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And here in the United States, a study of 650,000 individuals showed no decrease in longevity or mortality among those who exercised up to four times the minimum recommendation of 30 minutes five times a week.2 Do the math: Four times the minimum is 2 hours of exercise five times a week. Add to that the tons of studies showing the benefits of regular physical exercise for preventing cardiovascular disease, diabetes, cancer, Alzheimer’s, and depression and for improving quality of life—more energy, better daily living, greater happiness, a vibrant mind. So I’m feeling good about sticking to my running schedule, and I hope you are too.


Excerpted from Dr. Jordan Metzl's Running Strong