O'Keefe suggests that running damages the heart muscles.

Finally, Someone Thinks That Running 26 Miles Can Kill You

With the holidays approaching and waistbands ever-widening. it would seem like lacing the sneakers and hitting the pavement might be just what the doctor ordered. But there is gathering evidence that endurance sports like distance running actually, over the long run, hurt your heart.

An editorial in the British journal Heart suggests that endurance running over the long haul can damage the heart muscle, which is especially true for aging runners. Lead author Dr. James O’Keefe, head of preventive cardiology at the Mid America Heart Institute at Saint Luke’s Health System, points to studies that show subtle signs of heart damage in marathon runners.

Runners tested right after their races have been run showed scarring in their heart muscle. O’Keefe says his finding support data from the “Iron Mouse” study that found scarring in the hearts of mice forced to run long distances every day for four months.

The good news is that the mice seemed to improve after they stopped running and were allowed to return to “normal rodent life” — whatever that is. In other words, runners who give their hearts ample time to rest do not show the same damage over time.

But O’Keefe is worried that distance runners who keep at it year after year after year don’t ever give their hearts that chance.

“The heart pumps about 5 quarts per minute when we’re sitting,” he says. “When we’re running it goes up to 25 to 30 quarts. The heart wasn’t meant to do that for hours, day in and day out. You end up overstretching the heart and tearing muscle fibers. Up to 30 percent of those who finish marathons have elevated troponin levels, which is a marker for heart damage. That’s the marker we look for to see if someone’s having a heart attack – it’s irrefutable evidence of heart damage.”

MRIs of longtime marathoners shoe massive amount of scarring all over the hearts of longtime marathon runners.

The best proof of damage, according to O’Keefe, comes from two large studies that provided data on runners and life expectancy. One of those studies followed 52,600 people for up to three decades and included 14,000 runners and 42,000 non-runners.

Today summarizes the study:

“The good news was that the runners as a group had a 19 percent lower risk of death as compared to the non-runners. The bad news, for runners of marathons and the like, was that those who ran over 20 to 25 miles per week ended up with the exact same risk as the couch potatoes in the study.”

So what is the best exercise? O’Keefe maintains that the best way to prolong life is by vigorously exercising, no longer than an hour a day.

“The best prescription: run at a comfortable speed for a reasonable distance.”

Dr. Vonda Wright, a professor of orthopedic surgery and founding director of the Performance and Research Initiative for Masters Athletes at the University of Pittsburgh Medical Center, isn’t taken by O’Keefe’s study. The co-author of “Fitness after 40: How to Stay Strong at Any Age” says O’Keefe’s editorial is more like “documented blog than an actual study.”

The problem Wright finds is that the study doesn’t record the information on people’s hearts before the onset of the study.Wright maintains that it’s possible that some of the people doing the most running also had some issues with their hearts that the running “exacerbated.”

Besides, Wright says, “it’s not like every high level athlete who’s been racing for 25 or 30 years dies of heart disease.”

Wright points to her dad who just turned 73 and has been running marathons most of his life. “Until a few years ago he could beat my butt,” she says.

Wright is also concerned about the way O’Keefe’s editorial will be translated by the media. “I’d hate for this editorial to be translated in the media as a single line: “Running is bad for you and vigorous exercise can kill you,” she adds.