If we had a fast-twitch muscle fiber for every time we've heard "running will ruin your knees," we'd be able to outsprint Usain Bolt. And our knees would feel good while we did so, because despite what your potentially well-meaning but definitely ill-informed neighbors, co-workers, and relatives may have told you, there's no evidence that regular running damages knees.
That's not to say that no runners' knees ever bother them. But many knee problems in runners are the result of things going on elsewhere in the body, and most can be overcome with some simple changes.
Here are five things all runners should know about knees.
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1. Runners don't get arthritis in their knees more often than nonrunners.
Those are the facts. Period. If anything, long-term studies have found that runners have less incidence of knee osteoarthritis. One study that followed runners and nonrunners for 18 years found that, while 20% of the runners developed arthritis during that time, 32% of the nonrunners did. A large study that looked at runners and walkers found that regular runners had roughly half the rate of arthritis as regular walkers. In that second study, the runners with the highest regular mileage had the lowest rate of arthritis.
2. The above is true regardless of your age.
Some medical experts have said that loss of cartilage, including in the knees, is a natural part of aging. But there's no evidence that running accelerates that loss. In fact, at least one study found that when people who were at risk of developing arthritis began a moderate running program, the health of their cartilage improved, while the cartilage of a group of similar people who didn't start running didn't improve.
3. Supplements won't re-grow knee cartilage.
Despite ad claims, no dietary supplements have been proven to increase knee cartilage. The most popular such supplement, glucosamine, may help with knee osteoarthritis by protecting the articular cartilage, which, among other roles, helps to lubricate the knee joint. A study that looked at vitamin D supplementation in people who had knee arthritis found that they had the same levels of pain and loss of cartilage after two years as did people with arthritis who didn't take vitamin D.
4. Runner's knee is usually caused by issues elsewhere.
The most common knee injury among runners is runner's knee. Known clinically as chondromalacia patella or patellafemoral pain syndrome, it's inflammation of the cartilage under your kneecap. There's increasing consensus among sports medicine professionals that many people with runner's knee have a few common biomechanical problems. These include weak hips and glutes, which introduce instability further down the legs; weak quadriceps, which can make it difficult for the kneecap to track properly; and tight hamstrings, which shift some of running's impact to the knees. A good strengthening program, such as seen in this video, can go a long way to preventing runner's knee.
5. There are some simple ways to keep your knees happy.
As noted above, weakness and/or tightness elsewhere in your legs can mean trouble for your knees. So get stronger.
Extra weight places tremendous strain on your knees. The American College of Sports Medicine has said that each additional pound of body mass puts four extra pounds of stress on the knee. Running's long-term effect on keeping weight lower is thought to be a key reason why, as we saw above, runners might have less incidence of knee arthritis.
Run on level ground to lessen the torque on your knees.
If you have a history of knee pain, including from accidents or other sports, consider switching to more of a forefoot strike. One recent study found that more impact force affects the knees in rearfoot strikers, while forefoot strikers have more impact forces in their ankles.
