One of the most common questions I get in the office is whether or not running and other physical activities and sports are inherently bad for knees. In one sense, it is a completely logical conclusion. Repetitive impact to the bones and articular cartilage of the knee would seem to have detrimental effects long term and potentially lead to arthritis of the knee. But is there definitive evidence that running is bad for your knees?

Is running bad for your knees?

In the March 2011 issue of Medicine & Science in Sports & Exercise, the official journal of the American College of Sports Medicine, Donna M. Urquhart et al. present their results of a literature review to try to answer that question. They performed a thorough computer search for studies examining physical activity and evidence of cartilage damage. They found 28 studies that they felt were well designed and demonstrated evidence as to whether physical activity was related, positively or negatively, to radiographic signs (x-rays or MRI’s) of cartilage damage and/or arthritis.

Their results are somewhat surprising. The authors found that there is strong evidence for a relationship between physical activity and osteophytes (bone spurs), but there is no relationship between activity and joint space narrowing, which if present on x-rays would suggest that cartilage thickness is decreased. Most surprising was their conclusion that there was an inverse relationship between cartilage defects and physical activity, meaning that more active patients had fewer cartilage defects in their knees. Urquhart emphasizes that “physical activity is not detrimental to the knee joint but is actually beneficial to joint health.”

The benefits of running outweigh the risks

I have always felt that the benefits of physical activity (cardiovascular fitness, weight loss, mental health, etc.) far outweigh the risks to bones and joints. I would argue that even if arthritis of the knee develops, we have treatments for it. Overall health, to me at least, is more important than possibly needing a hip or knee replacement later in life.

This study is even more encouraging. While Urquhart et al. found a few studies that showed that physical activity seems to be related to bone spurs, there was no evidence of joint space narrowing of the knee. In fact, they found studies that demonstrated activity was beneficial to the articular cartilage volume and led to fewer cartilage defects. Essentially it seems to disprove the notion that running is bad for your knee. One could argue that a runner can have the best of both worlds – overall health benefits and arthritis prevention.

Consider adding cross training to your running routine

I will say that while I am excited that sports medicine physicians will be able to tell patients about the potential benefits of physical activity to articular cartilage of the knee, I think we have a long way to go to make definitive conclusions. The problem with these research studies is that there are a lot of variables such as weight, prior injuries, and surgeries. I would tell patients with known cartilage damage to the knee or prior injuries or surgeries to check with their orthopaedic surgeon and find out if running is potentially harmful. In those patients, adding non-impact activities (swimming, biking, using an elliptical trainer, etc.) can be mixed in with 2 or 3 days of running to improve health while still protecting the knee.

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