Running is supposed to delay death, not hasten it. Though stories of athletes dying mid-stride are as old as Phiddipides, the courier who (as myth has it) ran from Marathon to Athens in 490 BC bearing news of a Greek victory over the Persians, only to expire once he reached the agora, running deaths are exceedingly rare. The tragic exceptions make headlines, most recently the disappearance of ultrarunner Micah True in New Mexico’s Gila Wilderness. His body was discovered in March in a canyon, legs resting serenely in a stream. An autopsy later revealed an enlarged heart, but offered few clues as to why it had stopped beating.
True was 58 and a veteran ultrarunner, a man who, in his prime, logged 170 miles a week on the trail. What fells such an elite athlete?
A review in this month’s Mayo Clinic Proceedings presents evidence from several recent studies that “excessive endurance exercise”—the kind of training required for ultra marathons, Iron Man competitions, and long-distance bike races—may do lasting damage to the heart. While the results are far from damning—the data are often mixed—they suggest that, at a minimum, lacing up the running shoes and going gonzo does little to improve one’s health.
Chronic over-exercisers, writes Dr. James O’Keefe, lead author of the MCP review and a cardiologist at St. Luke’s Hospital, in Kansas City, Missouri, may develop scarring and calcification inside their ventricles and arteries. The medical term for this is “structural and electrical remodeling,” and it’s just what it sounds like: the slow hardening and thickening of the heart’s plumbing, the fraying of biological circuitry, due to years of strain.
Under such a theory, it wasn’t a 12-mile run that killed Micah True, but a lifetime of training and racing that may have permanently “remodeled” his heart in dangerous way, predisposing him to an arrhythmia, or wild, irregular heartbeat.
O’Keefe takes great pains to emphasize that running itself is not the culprit. “This in no way detracts from the importance of exercise,” he says. “Physically active people are much healthier than their sedentary counterparts. So much so that they, on average, live seven years longer than someone that doesn’t exercise at all.”
The problem patients are those who fail to see exercise as a game of diminishing returns. Just as drinking 10 beers doesn’t make me five times happier than drinking two, running ultra marathons doesn’t make me exponentially healthier than my friends running 5Ks. It just makes me sweatier, and insufferable at dinner parties.
O’Keefe points to a 15-year observational study of 52,000 adults, which found that runners had a 19 percent lower risk of “all-cause mortality” than non-runners. Good news, makes sense. Among the runners, though, those who logged big miles and high intensity workouts faired no better than those who ran less than 20 miles a week at sane paces. “These data suggest not only that more is not better, but in fact, more may be worse,” says Dr. Carl Lavie, a cardiologist at the Ochsner Heart and Vascular Institute, in New Orleans, who co-authored the study.