Overdosing With Too Much Exercise?

Is there such a thing as too much exercise? Parto and colleagues review the literature and say yes in their article, “The Exercise Rehabilitation Paradox: Less May Be More?” in Ochsner Journal’s fall cardiology issue.

The current obesity problem in our country indicates that many Americans do not get the World Health Organization’s recommended amount of exercise. But what about those who do? The authors’ intriguing paradox is that “sustained excessive endurance exercise” can have negative effects on a person’s health.

They pinpoint such issues as exercise training–induced cardiac remodeling that can increase long-distance runners’ risk of cardiomyopathy. The risk of osteoarthritis also increases with exercise, yet a runner’s tendency to have a lower BMI than nonrunners works to offset this risk. Long-distance runners were also found to be at a higher risk of coronary artery disease compared to those who exercised moderately or not at all, with shorter duration exercise bringing the maximum benefit for vascular function.

According to the authors, a U-shaped relationship exists between cardiac arrhythmia and exercise, with the risk beginning to increase as a person moves from moderate training to vigorous endurance training. As far as longevity is concerned, studies show another U-shaped curve, with higher intensity and quantity runners experiencing diminished gains compared to those who exercised more moderately. The article ends with the reassurance that “the overall benefits of running far outweigh the risks for most.” However, Parto and colleagues bring to light many considerations that will be of interest to endurance athletes.

For matters of the heart beyond exercise, check out the variety of topics in the fall cardiology-focused issue of Ochsner Journal.