I know, it's downright un-Bostonian of me to suggest that regularly running marathons is anything less than glorious. But a persuasive New Yorker article looks at the mounting evidence that extreme exercise really can be too much of a good thing — specifically, it may cause heart damage.
So if feeling anything less than super-fit has ever blocked you from working out, banish the sheepishness. From the New Yorker article, Extreme Exercise And The Heart:
[Cardiologist James] O’Keefe suggests that extreme exercise is “not conducive to great long-term cardiovascular health,” and cautions against the assumption that, if moderate exercise is good, more must be better. “Darwin was wrong about one thing,” O’Keefe says. “It’s not survival of the fittest but survival of the moderately fit.”
For those of us who believe that the “everything in moderation” rule applies to, well, everything, this argument makes sense. Exercise remains one of the best things you can do to improve your cardiovascular health, but you certainly do not need to run marathons to achieve the benefits. Moderate amounts of exercise throughout life are perfectly adequate. Athletes who exercise in extremes generally do so for reasons other than their health—competitiveness, professional requirement, compulsion. But recognizing that exercising more than a certain amount reaps no greater cardiovascular benefits is quite different than suggesting that this level of exercise causes cardiovascular harm.