How Much Is Too Much?
When it comes to exercise, I have the zealotry of the converted. As a kid, I faked asthma attacks to get out of the Presidential Physical Fitness Test, once missed my heat at a swim meet because I was in the locker room studying for a calculus test, and as a softball player, truly earned the nickname of Hardly Homerun Hobson. Then, in my 20s, I discovered running, and you couldn't shut me up about the virtues of exercise. I started doing marathons. When that got old, I took up triathlons and have now done several Ironman races. I insist, to everyone who asks whether 12 straight hours of exercise can possibly be good for me, that of course it is.
Except that sometimes, like during the last 10K of a marathon, when I start bargaining with my quads...I wonder if that much exercise can possibly be good for me. And a few studies I've seen, on what too much exercise might be doing to my heart, immune system, and the rest of my bod, had me wondering, too.
So I called Arthur Siegel, chief of internal medicine at the Harvard-affiliated McLean Hospital, who for years has studied nonelite Boston Marathon runners. Siegel runs the things, too, so I assumed he'd be a rabidly kindred spirit. And he agrees that getting a moderate amount of exercise is one of the best things you can do for your health. Not so racing 26.2 miles. "Marathon running is an overdose of a good thing," he said. That wasn't what I expected to hear. But Siegel has studied two phenomena that occur in marathons often enough to kill a handful of people every year. First is heart attack. A few years ago, he tested 60 marathon runners before and after the race, looking at their heart rhythms and their blood for signs of heart damage. After the race, 40 percent showed enough evidence to indicate damage, though that reversed within days. (The runners who trained the least had the most damage, suggesting proper conditioning is protective.)
Skip the race? The stress of running that long and that fast has a host of effects, including systemic inflammation and the promotion of blood clotting, both of which can lead to midrace heart attacks in people with some level of previously silent heart disease (and at a certain age, we almost all have some plaque in our vessels).
"I'm not saying don't do it," he says. "It's a great way to expand your knowledge of yourself and test your limits. But if you're a middle-aged person at risk for coronary problems, you should probably do the training and skip the race." Siegel has also studied hyponatremia, the potentially deadly condition that occurs when people in long endurance events take in too much water or sports drink. I consoled myself with the fact that I am not a middle-aged man and that I've gotten the hang of balancing my fluid intake. Like other racers, though, in the week following a big race, I often come down with a bug. And last season, I seemed to have a chronic sore throat, mild fever, and fatigue. Not to mention chronically crummy race results.