I am often asked whether running will cause premature development of knee arthritis. Many of my patients are very keen runners and, whilst they want to continue is to run, they also want to save their knees. Some also already have early joint wear. I have always given my patients the same advice. So long as their muscles are in good shape and their knees don't react by swelling or becoming painful after running, the health benefits of running will almost certainly outweigh the risks.
I am aware that many doctors advise such people (without good evidence) to stop running, and I have always disagreed with such blanket advice for all. At best it is wrong and at worst it deprives keen runners of something that they enjoy and that brings them physical and mental benefits. Humans are designed to be active, and the positive effects of being active are in the news more now then ever.
Now, the specific question about whether running can cause knee arthritis in healthy individuals has been looked at in a good study. The researchers measured the levels of harmful inflammatory chemicals in the knees of healthy runners aged between 18 and 35 before, and after they had run for 30 minutes. They found that the levels of these chemicals went down after running, but not after 30 minutes of other non-running physical activity. It therefore seems that running is actually chondroprotective ie. it prevents cartilage damage and wear.
Is this also true in older runners? Another study comes to the rescue. Researchers compared middle aged to older-aged long distance runners with a mean age of 58 years, to a group of healthy non-runners of the same mean age. The study looked at progression of arthritis on xrays taken at regular intervals. They found that there was no difference in the amount of arthritis in both goups, so running did not increase the likelihood of getting arthritis in older people. So even older people can enjoy the health benefits of running without worrying about their knees.
So I feel happy to continue to advise my active patients to keep running!