I am 48 and have been a runner for decades. When I mention that I run, I get told quite often that it is bad for my knees and I’ll end up needing knee replacements. Is this true? Will my running lead to knee pain? It seems as if the pounding your knees take from running should cause knee problems. Every step you take walking exerts a load on your knees 2-3x your body weight while running (depending on speed and form) loads your knees with 5-12x your body weight.

The Research

The common knowledge that running is bad for your knees is a myth. Research conducted over the past few decades has concluded that running is not bad for your knees (with a few caveats discussed below). David Felson from BU Medical School talking to NPR summarized the research: “We know from many long-term studies that running doesn’t appear to cause much damage to the knees,” he says. “When we look at people with knee arthritis, we don’t find much of a previous history of running, and when we look at runners and follow them over time, we don’t find that their risk of developing osteoarthritis is any more than expected.”

For example, in a study from 2017 of 2,600 runners and non-runners out of Baylor University concluded that “There is no increased risk of symptomatic knee osteoarthritis among self-selected runners compared with non-runners in a cohort recruited from the community. In those without osteoarthritis, running does not appear to be detrimental to the knees.”

This study from 2013 of 75,000 runners found that not only did running not cause knee deterioration, but that “running significantly reduced osteoarthritis and hip replacement risk due to, in part, running’s association with lower BMI.”

A meta-analysis from 2011 published by the American College of Sports Medicine found that physical activity, in general, was not detrimental to the knee joint and found “emerging evidence of an associated increase in cartilage volume and decrease in cartilage defects” suggesting that physical activity, including running, is good for the knee joint.

Running Might Be Good For Your Knees

Ross Miller, PhD of the University of Maryland led a study that focused on the bio-mechanics of running and found that “the relatively short duration of ground contact and relatively long length of strides in running seem to blunt the effect of high peak joint loads, such that the per unit distance loads are no higher than that in walking.” In discussing the research, Dr. Miller posits that “cartilage likes cyclical loading,” an activity in which force is applied to the joint, removed and then applied again. It was shown in animal studies that cyclical loading “prompted cartilage cells to divide and replenish tissue.”

Stephen Mayer of Northwestern University summarizes recent research as finding that “regular running strengthens the joints and actually protects against development of osteoarthritis later in life.”

According to Johns Hopkins School of Medicine, the greatest risk for knee arthritis is being overweight or obese. “Overweight women have nearly 4 times the risk of knee OA; for overweight men the risk is 5 times greater. Being overweight is a clear risk factor for developing OA. Population-based studies have consistently shown a link between overweight or obesity and knee OA.”

A Few Caveats

First, running may not be good for everyone’s knees. For those who are overweight or with poor bio-mechanics, running might cause additional wear and tear and lead to arthritis.

Second, running can cause knee pain unrelated to osteoarthritis. Patellofemoral pain syndrome, otherwise known as runner’s knee, is caused by overuse, poor form, flat feet or other bio-mechanical issues. However, runner’s knee is an acute injury and does not typically cause knee deterioration.

A Lesson

So, why does it seem that running leads to knee osteoarthritis? In the study out of Baylor mentioned above, the average research participant was 64 years old and of those that were regular runners at some points in their lives 33% had regular knee pain. However, the 43% of the non-runners had knee pain!

The lesson – as humans we seek explanation and causes and often jump to the most available explanation. If we know a runner with knee pain later in life that story/explanation sticks with us and we ascribe running as the cause. We fail to consider all the people we know with knee pain who are not runners note that non-runners have knee pain as well. In fact, of the people I know that have had or need to have knee replacements, I don’t think any of them are/were regular runners.