“What about your knees? how are your knees?” chances are, you’ve fielded those questions more than once. Not from physicians, exercise physiologists, or physical therapists but from nonrunning friends and family members who assume that pavement pounding wreaks havoc on our bodies and that we’ll all eventually need knee replacements and motorized scooters because of our arthritic joints.
Osteoarthritis (OA), the most common form of arthritis, occurs when cartilage, the spongy tissue that cushions our joints, breaks down and deteriorates, making weight-bearing activities painful. From there, many people believe that running accelerates this process. And while most of us credit our running for keeping our heart, lungs, and soul healthy and happy, a twinge in an ankle or stiffness in a knee makes us wonder if our nonrunning buddies are right and our joints are bearing an unreasonable burden.
The fact is if we run responsibly–wear supportive shoes and replace them when worn out, rehab injuries properly, incorporate cross-training and rest days into our schedules as needed–we’re no more susceptible to OA than the general population, say medical experts. Actually, it’s the doubters on the sidelines who could have a better chance of developing it.
Weighing In on Knee Pain
The number one risk factor for OA is excess body fat–a problem most runners don’t have. Sedentary, overweight people are 45 percent more likely to develop OA than those who are active. “The more you weigh, the more pressure is placed on the joints, which seems to accelerate the breakdown of cartilage,” says Patience White, M.D., chief public health officer for the Arthritis Foundation. Since losing weight is one of the best ways to prevent OA (losing 10 pounds can take about 45 pounds of pressure off the knee), and running is one of the most effective calorie burners, hopping on the treadmill for a tempo session could help you sidestep joint issues.
But running does more than just lighten the body’s load. “Aerobic exercise improves most body functions–including joint health,” says James Fries, M.D., professor of medicine at Stanford University School of Medicine. When you exercise, the cartilage in your hips, knees, and ankles compresses and expands. This draws in oxygen and flushes out waste products, nourishing and keeping the cartilage healthy. “Without exercise, cartilage cells get weak and sick,” he says.
Furthermore, running strengthens the ligaments that help support joints, making them more stable and less susceptible to sprains and strains, which can damage cartilage and eventually lead to OA.
In 2006, Dr. Fries presented research that compared rates of OA-related disabilities between 539 runners and 423 nonrunners over a 21-year period. At the follow-up exam, researchers found that the nonrunners were worse for wear–their increase in disabilities was twice that of the runners.
The runners in Dr. Fries’s study averaged about 60 minutes of running five days a week. But even higher-mileage runners don’t seem to risk bad knees. A 2006 study conducted at Germany’s University of Heidelberg looked at the incidence of OA among elite marathon runners. After comparing 20 former elite German marathoners with a control group of nonrunners of the same age, gender, and body mass index, the researchers found that the marathoners did not have a higher risk of OA of the knee.
When Injury Strikes
That said, while running itself doesn’t increase the risk of developing OA, running injuries can–especially when you delay treatment or rush recovery. Ankle sprains, in particular, have been linked to the development of OA. Almost half of those who twist or turn an ankle experience additional sprains or ongoing weakness and pain. This is typically because the original injury wasn’t well cared for and activity was resumed too quickly.
A 2005 study from the University of Basel in Switzerland found that 70 to 80 percent of patients with chronic ankle instability end up with arthritic ankles within 20 years. Doctors and physical therapists had always suspected this, but this was the first study to conclusively make the link between joint instability and arthritis, says Steven L. Haddad, M.D., associate professor of clinical orthopedic surgery at Northwestern University’s Feinberg School of Medicine. “Arthritis can occur because of uneven mechanics of the joint,” Dr. Haddad says. “If your joint is shifted and it’s even one millimeter off, it increases the stresses placed on that joint by 42 percent. This incongruity of the surfaces leads to an erosion of cartilage.”
This can also occur with patellofemoral pain syndrome, a.k.a. “runner’s knee,” says Dr. White. If you neglect strengthening the muscles and ligaments that support the patella (kneecap), it can become misaligned, causing pain and eventually OA (see “Preventive Steps,” left, for strength-building exercises). “If the patella is tracking just a little bit off, it can rub the cartilage in an abnormal way and wear it down,” Dr. White says.
Luckily, all of this is avoidable. As Dr. White advises, “Don’t run through joint pain, stick to soft surfaces when possible, wear supportive running shoes, and include strengthening exercises in your routine.” Addressing joint issues sooner rather than later will not only help you avoid long-term damage, but it’ll also help you run circles around your nonrunning friends for years to come.