In recent years, the health effects of increasing inactivity have received plenty of scientific and media scrutiny. But the potential health effects of relatively gargantuan levels of physical activity have received less attention, and much of the science that does exist focuses on the potential dangers of over-exercise for the heart. Few studies have examined the more general health implications the benefits as well as the risks of training for and running more miles in a day than many of us complete in a month.
Hoping to better understand what happens to an ultra-endurance athletes 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.
Then they compared the ultra-runners aggregate answers with comparable health statistics for average, more sedentary adults, while also comparing the training and injury-related data with similar information about recreational runners, like myself, who are not running 50- or 100-mile races on the weekend.
The results, which were published last week in PLoS One, were telling. The ultra-runners had a low, although not non-existent, incidence of high blood pressure and irregular heartbeats, with about 7.5 per cent of the runners reporting one of those problems. But less than 1 per cent had been diagnosed with heart disease or had a past stroke, and few had experienced cancer, with basal cell skin carcinoma being the most common malignancy, occurring in 1.6 percent of the runners.
On a less salutary note, the runners did report a high incidence of breathing problems, with almost a third of the group telling researchers that they experienced either allergies or asthma, often after running. That finding, while worrying, makes sense, the researchers note, since ultra-long-distance runners spend many hours outside, striding along trails strewn with pollen-slinging trees and flowers, priming their respiratory systems for allergies and asthma.
They also tend to get hurt, as runners at all mileage levels do. More than half said they had experienced a running-related injury in the past year that had been severe enough to keep them from training for at least a few days, about the same percentage as often is reported by recreational runners. Many of the injuries were knee problems or stress fractures, along with a few, unexpected concussions.
Interestingly, injuries were most common among younger, inexperienced ultra-runners, and in particular among men not yet aged 40 who trained fast and intensely. Ultra-runners past age 40 whose training pace was more plodding were far less likely to be sidelined with injuries.
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.
- GRETCHEN REYNOLDS