Perhaps because it seems intuitively true, the notion persists that running, especially when done long-term and over long distances, is bad for the joints. Indeed, it would be hard to think otherwise when with each foot strike, a runner’s knee withstands a force equal to eight times his or her body weight — for a 150-lb. person, that’s about 1,200 lb. of impact, step after step.
The common wisdom is that regular running or vigorous sport-playing during a person’s youth subjects the joints to so much wear and tear that it increases his or her risk of developing osteoarthritis later in life. Research has suggested that may be at least partly true: in a study of about 5,000 women published in 1999, researchers found that women who actively participated in heavy physical sports in their teenage years or weight-bearing activities in middle age had a higher than average risk of developing osteoarthritis of the hip by age 50.
But over the past few years, an emerging body of research has begun to show the opposite, especially when it comes to running. Not only is there no connection between running and arthritis, the new studies say, but running — and perhaps regular vigorous exercise generally — may even help protect people from joint problems later on.
In a well-known long-term study conducted at Stanford University, researchers tracked nearly 1,000 runners and nonrunners
