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Every runner has been told once, or twice, or every day by someone they know, that this sport will wreak havoc on the knees. This kind of “advice” might have you wondering if running really is bad for your knees and whether you should dial back on clocking miles, or trade in your running shoes for a helmet and a bike.
The whole notion that running will ruin your knees is based on the idea that running increases your risk of developing osteoarthritis in this key joint of the leg. But the truth is, it doesn’t.
Below we explain the evidence and offer an explanation for why running doesn’t destroy your knees. We’ll also examine how best to lower your risk of incurring the most common running-related knee injuries. Armed with this knowledge, you should be able to be a living refutation to the idea that running will eventually ruin your knees.
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Is running bad for your knees?
This should be stated as clearly as possible: Numerous studies have shown that runners have lower rates of knee osteoarthritis than sedentary people. For example, in one study published in 2008 that followed runners and non-runners for almost 20 years, X-rays showed signs of arthritis in the knees of 20 percent of the runners, but 32 percent of the non-runners.
A potential counterargument against such results is that, when the studies are started, the long-time runners that take part have above-average structural health—they don’t include people who started running, but had to give it up because their bodies broke down.
However, research has rebutted that idea as well. A study published in 2017 followed more than 2,000 people for several years to see how many developed arthritic knees. The participants gave detailed information about how often and how severely they had knee pain. They also described their current and former exercise habits. In other words, the participants weren’t selected because of whether they were or weren’t runners.
But it turned out that running status did matter. In frequency of knee pain, symptoms of arthritis, and evidence of arthritis on X-ray, current runners had significantly better scores than non-runners. For example, current runners were 29% less likely than non-runners to report frequent knee pain. Even former runners were less likely to report knee pain and show signs of arthritis than non-runners. That last finding is the opposite of what should be the case if running ruined their knees and caused them to give up the sport.
There’s also good evidence that running and knee arthritis isn’t a case of play now, pay later, particularly in terms of running increasing your chances of physical limitations as an older person. In a study published in 2008 in JAMA, researchers matched members of a running club with healthy non-runners; all the study participants were at least 50 years old at the beginning of the study. The researchers followed up with the participants 21 years later. Not only were more of the runners still alive, but they also reported significantly fewer physical limitations.
Part of the researchers’ conclusion was that “running at middle and older ages is associated with reduced disability in later life.”
How can running help stave off osteoarthritis?
To answer this question, it helps to know current thinking on osteoarthritis.
Arthritis is inflammation in joints, the points in your body where bones come together (knees, hips, wrists, etc.). Osteoarthritis is arthritis characterized by thinning and breakdown of cartilage, the protective tissue at the ends of bones. Osteoarthritis used to be considered a “wear and tear” disease, with body parts seen as analogous to machinery that inevitably breaks down. That model is no longer widely believed by medical experts. Instead, osteoarthritis is considered a disease of the joint, with multiple potential causes.
With this more nuanced understanding of osteoarthritis, running’s potential protection against developing it makes more sense.
One possible mechanism may be lower body mass index (BMI) in runners compared to the general population. In one long-term study, runners had lower rates of osteoarthritis and hip replacements than walkers and other more casual exercisers. The researchers cited the runners’ lower BMIs as one of the probable explanations.
There’s also good evidence that, as with the rest of your body, knee cartilage is subject to the use-it-or-lose-it principle. Rather than breaking down your joints, running helps to keep them lubricated. Researchers have found that running conditions your cartilage to become more resilient as it adapts to the demands of running. And a meta-analysis published this year found that cartilage recovers well from a single bout of running, while adapting over time to the exposure. Sedentary people who have developed osteoarthritis are advised to exercise regularly for these very reasons.
Can you still run if your knees are in bad shape?
It’s one thing to say that running will likely lower your risk of developing knee osteoarthritis. But if you already have it, or some other chronic knee issue, is running out of the picture for you?
Research in this area is encouraging. One study followed people who were at least 50 years old and had osteoarthritis in at least one knee. At the end of the eight-year study, runners reported less knee pain, and imaging showed that their arthritis hadn’t progressed.
In a four-month study published in 2019, including middle-aged people, imaging found evidence of damage (not necessarily arthritis) in most of the people’s knees. After half of the study subjects did a four-month marathon training program, MRIs of their knees showed less damage than at the start of the study. That finding meshed with the results of a study published in 2005 that found that, after four months of moderate exercise, knee cartilage health improved in middle-aged people at risk of developing osteoarthritis.
“Listen to your body” is excellent advice for all runners. In the case of runners with preexisting knee pain, that means to let your symptoms guide you in how much running, and what type, is tolerable. Take heart that as you go about this trial-and-error process, there’s good reason to believe running won’t worsen your condition over time.
How can runners lower the risk of knee pain or injuries?
None of this is to suggest that runners are immune to knee injuries. One study published in 2020 revealed that the knee was the most common location for running-related injuries, with the foot and ankle, lower leg, and hips or pelvis following, respectively, for most commonly affected areas. More specifically, the most common injuries were patellofemoral pain syndrome, the iliotibial band friction syndrome, and patellar tendinopathy.
But it’s important to remember that most running knee injuries, like most running injuries in general, are overuse injuries. They’re caused by more cumulative stress to a given body part than your body is currently equipped to handle. Knee injuries aren’t a given, and they aren’t likely to cause permanent damage unless you ignore them and don’t try to fix the underlying issues that led to the injury.
There’s a growing body of research suggesting that knee injuries are often caused by weakness or instability elsewhere in the body, especially the hips. That’s why strengthening programs for avoiding or overcoming knee injuries often focus on exercises for your quads and glutes.
If you have a history of knee injuries, you might also benefit from slightly (slightly!) altering your running form.
Backed by research, many sports medicine experts advise increasing your running cadence (the number of steps you take in a minute) by 5% to 10% if you can’t seem to shake knee injuries. The reason: A shorter, quicker gait should shift running’s impact forces from your knees to your lower legs. Although there’s no one ideal cadence for all runners, if you can see your feet making first contact with the ground when you run, you’re probably overstriding. Doing so places enormous braking forces on your knees, and is linked to an increased risk of injury.
