It’s an unsettling headline: “When exercise does more harm than good.” Isn’t running supposed to be great for you? After all, it can even add 6.2 years to your life, according to a recent study.
But when James O’Keefe, M.D., a cardiologist at the Mid America Heart Institute, and a team of researchers focused just on extreme athletes, they found something different. The protective effect of running dwindled. In fact, it reversed.
Veteran endurance competitors were five times as likely to experience a fast, irregular heartbeat that can lead to stroke when compared to the general population, according to the report. (It makes us question: Can Running Kill You?)
“When my patients ask my advice about doing a marathon, full-distance Ironman triathlon, or even half Ironman, I tell them to do it once, cross it off their bucket list, and focus on healthier, long-term exercise patterns,” Dr. O’Keefe says. Why? The stress on your heart and blood vessels from excessive, strenuous exercise can cause “enlargement, thickening, stiffening, disease, and predispose to dangerous rhythms, heart failure and heart attacks, in extreme cases,” Dr. O’Keefe explains.
The threat can be immediate, too. Although all return to normal within a week or so, extreme exercise can temporarily reduce your right ventricle’s ability to pump blood, setting the stage for a dangerous heart rhythm, according to the report.
But here’s the good news: Heart damage is generally a cumulative process–meaning, it’s not likely to happen after a single marathon. Ultra-athletes are usually sweating it out for up to 5 hours a day–five to 10 times the weekly recommended dose of exercise. (Pressed for time, but still want to break a sweat? Pick up the Men’s Health Big Book of 15-Minute Workouts!)
Your move: To avoid the highest risk, limit your huffing and puffing to 40 or 50 minutes a day–no more than 7 hours a week, says Dr. O’Keefe. Keep your speed around 6 or 7 miles per hour and your distance under 20 miles, too.