Dear Runners, Stop Worrying About Your Knees From: A Physiotherapist and Distance Runner

Chances are, if you are a runner, you have been a victim at some point to the dreaded small-talk with a well-intentioned stranger about bad knees. You may get roped into talking about your own bad knees, or their bad knees, or their friend’s Aunt-who-ran-boston-once’s bad knees.

I am going to make a generalization and say that when we say “bad knees” most of the time we are referring to knee osteoarthritis, a degenerative condition of the knee joint. Funny enough, and despite what you have heard from your doctor, or your running partner, or your friend’s Aunt-who-ran-boston-once, recreational running DOES NOT CAUSE OSTEOARTHRITIS. In fact, it may actually prevent it. And it is time that we start to change the conversation about running and our knees.

What Is Osteoarthritis?

Before we delve into running, it is important to know a little bit about about Osteoarthritis, (or OA). If we break down the greek origin of the word, osteoarthro, and itis simply means bone,joint, and inflammation. Essentially, the progression of osteoarthritis involves the wear and tear of the cartilage that covers the ends of the bones within the knee joint, resulting in inflammation and oftentimes pain. Terminology can sometimes be unnecessarily scary. For example, what if I told you that my friend has heterochromia. Sounds terrible, until you learn that heterochromia just means she has one eye that’s blue and one eye that’s green, with no negative impact to her health whatsoever. Personally, I prefer the word degeneration over the word osteoarthritis because it better describes a fairly normal part of the aging process, and something that can be managed rather than cured.

Knee OA accounts for 80% of all OA diagnosis, and affects at least 19% of American Adults over the age of 45 [1]. The prevalence of OA has doubled since the mid-20th century and is the leading source of chronic pain in developing nations [1]. This is likely due to increases in BMI, sedentary lifestyle, and life expectancy. The diagnosis of OA can be made radiographically, ie with X-ray. However, interestingly enough, your X-ray results have very little correlation with symptoms [2]. This means that one person might have debilitating pain and fairly mild OA findings on X-ray, and  another person’s X-ray could show advanced degeneration but he may be absolutely pain-free. This is another reason that I caution clients not to be frightened by a diagnosis of OA.

What is the relationship between running & osteoarthritis?

It would make sense that high impact, repetitive mechanical stress to the knee joint might result in a degenerative wear and tear condition such as osteoarthritis. On the other hand, we also know that movement is imperative to joint health. So what does the research tell us?
Initially, the relationship between knee OA and running was studied among top-level elite male distance runners. In these early studies, there appeared to be an increased risk for these athletes to develop OA. The results of this research helped to influence clinicians’ recommendations to all runners, without considering that the vast majority of runners would not meet the inclusion criteria for these studies. The research we have now (on everyday runners like you and I) paints a much different picture.

In 2017, a large multi-centre study of men and women ages 45-79 was published debunking the relationship between running and OA risk [3]. Not only did it fail to prove that individuals who currently run, or have run at some point in their lives have a higher prevalence of OA, (symptomatic and radiographical) but there was a dose-dependent inverse association with running and knee pain. What this means is that frequent runners were shown to have the lowest prevalence of knee pain, followed by infrequent runners, and  individuals who have run at some point in their life. Finally individuals who have never run report the highest prevalence of knee pain.

There are many hypothetical reasons why running may actually be protective of OA. The first is that it can help mitigate some of the OA risk factors that have been identified above such as high BMI, and a sedentary lifestyle. There are some researchers that believe there could be more to the story. One hypothesis suggests that while cartilage in the knee acutely weakens right after running, it may grow back stronger and thicker over time, as a reaction to repeated training [4] . Much like lifting weights will create acute micro tears in the muscle in response to a hard workout, and will build bigger stronger muscles over time with repeated training. Some researchers believe that running is the same for your joints. But just like you wouldn’t bench press 400 lbs or run a marathon on day 1 of your training plan, a gradual increase of mileage of 10% or less per week, with adequate rest to promote healing is thought to improve knee cartilage in the long term. Though this type of research is still in its early stages, it is thought-provoking.

Public perception plays a role

I hear it every week, “my doctor told me I shouldn’t run”. While the majority of current research debunks the old-school belief that running is bad for your joints, the perceptions of some medical practitioners, non-runners, and even runners themselves are stuck in the past. In a 2018 study that surveyed Canadians (including health care practitioners) 80% of runners said they would decrease their running if they were diagnosed with OA [5]. Almost half of all surveyed believed that running with Knee OA would make the condition worse, and more than half believed it would result in a premature total knee replacement. Among healthcare practitioners surveyed nearly a quarter thought that long-distance running was a risk factor for developing OA, and nearly 40% would recommend modifying their training programs after diagnosis. Three percent of healthcare practitioners would recommend quitting altogether.

What if I already have osteoarthritis?

The first study to look at runners who already have OA was published in 2018. It compared the X-rays of runners and non-runners with OA at baseline and 48 months later. Luckily, runners did not show increased disease progression compared to non-runners [6]. Not only did running not appear to be harmful for OA, but there was less knee pain reported among runners compared to non-runners. While more research needs to be done, the results are promising.

At the end of the day, running and running injuries are highly individual. OA is no different.My intention of this article is not to paint with a broad brush, but rather to encourage discussion and critical thinking. Certainly there are clients who could benefit from treatment and modifications to their running program in order to recover from an acute flare up of OA symptoms. Thankfully, physiotherapy can help in all stages of OA to increase strength and range of motion, decrease pain, and improve function and quality of life. But if you have been told that you should not be running, especially if this recommendation is permanent, then perhaps you should be asking why? And if that answer is not satisfying, perhaps it is time for a second opinion.

To book an appointment with Laura Gfeller, PT or one of our other health care professionals at Choice Health Centre call (902) 404-3668 or book an initial assessment online.


  1. Wallace, Ian J., et al. “Knee Osteoarthritis Has Doubled in Prevalence since the Mid-20th Century.” Proceedings of the National Academy of Sciences, vol. 114, no. 35, 2017, pp. 9332–9336., doi:10.1073/pnas.1703856114.
  2. Zhang, Yuqing, and Joanne M. Jordan. “Epidemiology of Osteoarthritis.” Clinics in Geriatric Medicine, vol. 26, no. 3, 2010, pp. 355–369., doi:10.1016/j.cger.2010.03.001.
  3. Lo, Grace H et al. “Is There an Association Between a History of Running and Symptomatic Knee Osteoarthritis? A Cross-Sectional Study From the Osteoarthritis Initiative.” Arthritis care & research vol. 69,2 (2017): 183-191. doi:10.1002/acr.22939
  4. Miller, Ross H.. “Joint Loading in Runners Does Not Initiate Knee Osteoarthritis.” Exercise and sport sciences reviews 45 2 (2017): 87-95 .
  5. Esculier, J. F., Krowchuk, N. M., Li, L. C., Taunton, J. E., & Hunt, M. A. (2018). What are the perceptions about running and knee joint health among the public and healthcare practitioners in Canada?. PloS one13(10), e0204872. doi:10.1371/journal.pone.0204872
  6. Lo, G.H., Musa, S.M., Driban, J.B. et al. Clin Rheumatol (2018) 37: 2497.

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