Can you get too much exercise? What the heart tells us

Study after study shows that people who meet the standard exercise guidelines, which call for about 30 minutes a day of moderate exercise, have a reduced risk of developing heart disease.

Many middle-aged marathon runners and other endurance athletes are familiar with concerns from their loved ones — and occasionally their physicians — that they might be exercising too much and straining or harming their hearts.

For all of them, a large-scale study published recently in JAMA Cardiology should be mollifying. It finds that middle-aged men who work out often and vigorously do tend to develop worrisome plaques in their cardiac arteries. But those men also are less likely than more sedentary people to die prematurely from a heart attack or other cause.

The findings raise the interesting possibility, in other