Is It Possible to Exercise Too Much?

A slew of new studies sleuth it out

The New York Times published a missive this week examining several new studies which looked at the effect of prolonged endurance exercise on athletes’ hearts. The outcomes, both mixed and intriguing, are leading some people to wonder: Is it possible to exercise too much, such that the benefits of exercise—a stronger heart, for example—suddenly turn a corner and have a negative impact on health?

Listen to this:

For some time, exercise scientists, as well as a few highly committed exercisers and their spouses, have wondered if there might be an upper limit to the amount of exertion that is healthy, especially for the human heart. While the evidence is overwhelming that exercise improves heart health in most people and reduces the risk of developing or dying of heart disease, there have been intimations that people can do too much. A 2011 study of male, lifelong, competitive endurance athletes aged 50 or older, for instance, found that they had more fibrosis — meaning scarring — in their heart muscle than men of the same age who were active but not competitive athletes.

Now the latest Vasaloppet study [which looked at athletes who completed a grueling 56-mile cross-country ski marathon held each March in northwestern Sweden] and a separate study of rats running the equivalent of several rodent marathons that was published this month in The Journal of the American College of Cardiology are likely to further the debate about possible upper limits to safe exercise. Providing some counterbalance, though, is another animal study, published this month in PLoS One, that suggests that even if strenuous prolonged exercise increases the chances of some arrhythmias, it may lessen the chance of suffering fatal heart problems.

In other words, the results that one study points at, another denies, with shade of variance in between. But it’s an important issue to be aware of, I think, and to know that researchers really don’t know how prolonged endurance exercise impacts the body—for better or worse. So it’s another reminder for you to listen to your own body—you are your own best expert, after all—and take it easy when you think you need to.

Read the full Times report here.

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