Is Running Bad for your Knees?

​“You’ll hurt your knees if you run.”
 
This old yarn has been spun for decades…but is it true??
 
Conventional thinking has long believed that “running is bad for your knees,” largely based on anecdotal observation and blanket assumptions. Yes, runners are injured a lot (much of it self inflicted through poor training choices, not the inherent act of running). But does high prevalence of overall injury equate to chronic “bad knees”?

​A meta-analysis (aka, really big study looking at a bunch of other papers) from 2017 by Alentorn-Geli, et al, examined several studies encompassing over 100,000 runners of all levels and control groups of non-runners to see if any association existed between running and arthritis. 
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Bottom line up front: Amateur runners (non-professionals) experience LOWER rates of hip and knee OA compared to runners who compete for money or people who don’t run at all. Among the amateur runners, the OA rate was 3.5% whereas more than 10% of the non-runners experienced OA, as did more than 13% of the professionals. (Also of note was that running for less than 15 years was associated with lower OA rates).
 
Based on these findings from a large set of data, running actually could be good GOOD for your joints, when done below the professional level. This makes physiological sense when viewed through the lens of Wolff’s Law, which states that bone will remodel in response to the forces or demands placed upon it. If you expose bone to repeated stressors of running it will grow stronger along the lines of forces applied. But we also know that with any stressor applied to the body, any excess force beyond the body’s ability to adapt can lead to undesirable changes, such as injury or chronic strain.
 
A subsequent 2018 study by Ponzio et al (thus not included in the 2017 meta analysis) on marathon runners of all levels found that age, family history and surgical history were predictive of hip or knee OA, but there was also NO significant risk associated with running duration, intensity, mileage, or the number of marathons completed. Additionally United States marathon runners in this sample experienced significantly lower OA rates (8.8%) as compared to the US average (17.9%).
 
Do runners get hip and knee OA? Yes, of course. But so do people who don’t run at all…and those people seem to get MORE OA than amateur runners by a notable margin.
 
Take home point: ALL types of people develop knee problems through the normal course of aging. Some happen to be runners, some don’t run. While intense training levels from the professional level seem to be related with increased OA signs, if we are to infer any causation from evidence, it would be that modest amounts of running could be protective against OA. Regardless, it would seem there’s enough evidence to cast significant doubt on the old suspicion that “running is bad for your knees.”

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