It’s a common enough belief: running ruins your knees over time. Based on the number of former runners out there with bad knees, anecdotal evidence seems to bear this out.
But appearances are deceiving. Recent studies indicate that it’s not the act of running, but injury that causes knees to wear down.
The New York Times Well blog had a piece yesterday highlighting several studies that say running doesn’t contribute any more to the development of osteoarthritis—the progressive wear and tear of protective cartilage—than walking does. In fact, in terms of impact on the knee, “running and walking are essentially indistinguishable,” one study author told the blog.
The news is particularly good for distance runners. From the Times:
An impressively large cross-sectional study of almost 75,000 runners published in July, for instance, found “no evidence that running increases the risk of osteoarthritis, including participation in marathons.” The runners in the study, in fact, had less overall risk of developing arthritis than people who were less active.
A small study of 14 people published this month in the journal Medicine and Science in Sports and Exercise may explain why. According to the researchers at Queen’s University in Kingston, Ontario, running caused much more force to travel through the knee than walking did—no surprise there. But they also found that runners’ feet only touched the ground for a fraction of the time that they did when walking. These opposing factors ended up canceling each other out, according to the paper.