On Tuesday, March 27, ultrarunner Micah True set off for a 12-mile run through New Mexico’s Gila National Forest and didn’t return. Four days later, a search party of his friends found him dead, bruised, and lying on his back with his legs in a stream. Roughly five weeks later, on May 7, the New Mexico Office of the Medical Investigator released an autopsy that said True died of idiopathic cardiomyopathy—heart disease with an unknown cause.
More specifically, True had dilated cardiomyopathy. The wall of his heart was enlarged and stretched thin, which would have made it increasingly ineffective at pumping blood throughout his body. As Tom Meersman explained in a breakdown of the autopsy for Runner’s World: “What autopsy reports can’t tell us definitively is what killed True. It’s reasonable to imagine a situation in which a runner with dilated cardiomyopathy and mild dehydration, who is out on a run, has their cardiac output decrease to the point of medical emergency. Was this the (im)perfect storm that killed Caballo Blanco? We will never know for sure.”
Still, at least one cardiologist suggested that the cause of True’s death could have been the result of chronic excessive endurance exercise, according to a recent Outside article by Erin Beresini. That cardiologist was James O’Keefe, the director of the Preventive Cardiology Fellowship Program at Missouri’s Saint Luke’s Mid America Heart Institute. He and fellow cardiologist Chip Lavie have published several exercise reports in the past two years suggesting that people who run for longer distances for prolonged periods of time have more adverse health effects and a higher mortality than those who run for shorter periods of time. The scientists have also said that extreme runners have fewer adverse health effects and a lower mortality than the population as a whole. As Beresini reports, what those scientists have suggested is still being called into question by their peers.
Amby Burfoot of Runner’s World conducted a solid interview with both cardiologists about what they’ve found. The takeaway from that interview came from O’Keefe, who said: “The latest data from our studies and others strongly suggests that the ideal dose of daily vigorous exercise is about 30 to 60 minutes. Heck, you can get the majority of improvements in cardiovascular risk and longevity with a mere 20 to 30 minutes of walking per day. If you do more than 60 minutes of strenuous exercise daily, you start to lose some of the health benefits seen with lesser amounts of physical activity.”
That’s not to say what the scientists have shown is definite. In multiple posts, Alex Hutchinson, who writes Runner’s World's Sweat Science blog, pointed to issues with the scientists’ methods. Burfoot summed up his thoughts on the studies and what they show quite effectively in a separate post. “Many aspects of exercise and running also follow a U-curve,” he wrote. “This is why many people believe the moderate approach is the smartest path to follow. Of course, you’ll never qualify for the Boston Marathon that way. We all have to make our choices.”