It was "reported that runners, regardless of the age when they ran, had a lower prevalence of knee pain and osteoarthritis ... Regular running, even at a non-elite level, not only does not increase the risk of developing knee OA but may protect against it, the researchers concluded.

"This does not address the question of whether or not running is harmful to people who have pre-existing knee OA," said Dr. Lo. "However, in people who do not have knee OA, there is no reason to restrict participation in habitual running at any time in life from the perspective that it does not appear to be harmful to the knee joint."

Science is making leaps and bounds. Have a degenerative disc in your back? One day you might be able to grow it back!