Not long ago, researchers studied the heart health of a group of very fit older athletes -- men who had been part of a national or Olympic team in distance running or rowing, and runners who had completed at least a hundred marathons. The results were unsettling -- half of these lifelong athletes showed evidence of heart muscle scarring.
The affected men were invariably the ones who had gone through the longest, hardest training. And now a new study, this time in laboratory rats, provides solid evidence of a direct link between certain kinds of prolonged exercise and heart damage -- scarring and structural changes, similar to those seen in the human endurance athletes.
The research effectively shows that years of strenuous cardiovascular exercise can damage your heart.
According to the New York Times:
"Unfortunately, it remains impossible, at the moment, to predict just what that threshold is for any given person, and which athletes might be most vulnerable to heart problems as a result of excessive exercise".