"What Ultra-Marathons Do to Our Bodies"

Very little, apparently, except make us healthier than average.

"...Hoping to better understand what happens to an ultra-endurance athlete’s body, researchers at Stanford University and the University of California, Davis recently contacted more than 1,200 experienced ultra-marathon runners and asked them probing and almost impolite questions about the past and current states of their bones, hearts, blood pressures, prostates, breasts, skin, lungs, moods, bowels, eyes, waistlines, livers and many other body parts and systems. They also asked about their race histories, times, training regimens and any recent injuries and illnesses....

"...And there can be substantial, accruing benefits to covering those miles, says Dr. Eswar Krishnan, an assistant professor at Stanford and co-author of the new study. Over all, the ultra-runners in the study were absent from work less often than other American adults because of illness or injury, he said, and rarely felt compelled to see a physician, with almost half visiting a doctor only once in the past year, usually because of a running injury.

"Of course, the ultra-competitors may have “developed stoicism” from their many hours of training, Dr. Krishnan said, and ignored niggling ills that would keep the rest of us from work or send us hurrying to the doctor. But they also displayed a substantially reduced risk of developing many of the common diseases of modern life...."

No surprise to me. This is what we evolved to do.

From the study:

The present work provides an analysis of medical issues in a large cohort of ultramarathon runners. As expected, the work demonstrates that, with the exception of asthma and allergies, ultramarathon runners have fewer chronic medical conditions than the general population, tend to miss little time from work or school due to illness or injury, and make limited use of the medical care system.

So go run. I'll note that most of the injuries they describe could be reduced with a barefoot-style running form...