how much exercise is too much

Can You Exercise Yourself to Death?

It’s pretty hard to exercise too much. That’s the conclusion from a new analysis of physical activity published in June in the journal JAMA Internal Medicine.

The authors combined results from six studies with a total of 661,137 people.  In each of these studies, the researchers asked participants how much of their leisure time they spent exercising. Then the researchers kept track of who lived and who died.

On average, the studies followed these subjects for 14 years, during which 116,686 died. Those who exercised more died less.

How Much Exercise Is Too Much?

This study compared exercise levels to the official U.S. government recommendations: 75 vigorous-intensity or 150 moderate-intensity minutes of physical activity per week. To give you a rough idea, moderate activities include activities like brisk walking, cycling and doubles tennis. Vigorous activities include running, soccer, or singles tennis.

In general the more exercise, the less risk of death…. up to a point. Compared to people who sat on their butts all day, here’s how much the other folks cut their risk of death:

  • Some exercise, but less than the recommended amount: 20%
  • One to two times the recommended amount: 31%
  • Two to three times the recommended amount: 37%
  • Three to five times the recommended amount: 39%
  • Five to ten times the recommended amount: 39%
  • More than ten times the recommended amount: 31%

If you graph these numbers, you end up with a reverse J-shaped curve, suggesting that people getting much more than 10 times the recommended dose of exercise may actually be doing themselves harm. But the authors don’t present the data that way.

Instead they write:

These findings are informative for individuals at both ends of the physical activity spectrum: they provide important evidence to inactive individuals by showing that modest amounts of activity provide substantial benefit for postponing mortality while reassuring very active individuals of no exercise-associated increase in mortality risk.

It would be fascinating to keep plotting the curve out to capture extreme athletes and see if they were ever at increased risk of dying. Bu the truth is that very few people get that much exercise.

And this study didn’t have a large enough population of extreme athletes to do that. Other studies in these populations have reached mixed conclusions.

So go out and run 20 miles a day if you want. I’ll try to keep up with you.

Photo: “The Death Blow” by Arallyn!

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3 thoughts on “Can You Exercise Yourself to Death?”

  1. Hi Laird,
    It seems like so many of these studies don’t provide solid evidence for their claim. It’s correlation verses cause. For example, those who exercise more also tend to have an overall healthier lifestyle with regard to such things as food, health care/insurance, and dental hygiene. These factors could also contribute to living longer, even if one didn’t exercise a lot.

    and on another note.
    What do you think about “Z” health?

    1. It’s a good point, Sandra. These authors did not control for such factors. However there is good evidence from trials in which people are randomly assigned to exercise or not to exercise, that those who exercise experience measurable health benefits. For example one study found that people who exercised more improved their insulin sensitivity and glucose tolerance compared to people who didn’t exercise.

      I don’t know anything about Z-Health. The website I found, is pretty vague.

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