If you are a runner, either indoors or out, you’ve probably heard at one time or another: “That must be hard on your knees.” Or perhaps if you are considering taking up running, friends and colleagues who don’t run are warning you about the impending havoc that will be wreaked on your knees should you start. There is a common misperception among non-runners that running automatically leads to knee replacement surgery and osteoarthritis. However, doctors, exercise physiologists, physical therapists, and of course, runners, know this is just a myth.
Osteoarthritis of the knee is a serious and common disorder. It occurs when the spongy tissue in our joints known as cartilage deteriorates and breaks down, and many people believe running exacerbates this process. However, use of the right kinds of shoes, good running technique, good exercise habits in general (including adequate rest and cross-training), result in runners having no greater risk of osteoarthritis than anyone else. In fact, running may be protective to the knees and some runners have less osteoarthritis of the knee than their non-running counterparts.
Interestingly, the biggest risk factor for osteoarthritis is excessive body fat levels. In fact, just 10 extra pounds adds about 45 pounds of pressure on the knees. People who are overweight and/or sedentary are 45 percent more likely to develop osteoarthritis than those who are of normal weight who exercise regularly. "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.
Most runners do not have excess body fat, because running is one of the most efficient calorie-burning exercises you can do. Any kind of weight-bearing aerobic activity is good for your joints. James Fries, M.D., professor of medicine at Stanford University School of Medicine says, "Aerobic exercise improves most body functions--including joint health. 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.
Dr. Fries’s and his team conducted a 21-year research study that compared rates of osteoarthritis-related disability among runners and non-runners. Despite running 5 days a week, for 60 minutes a session, the 593 runners in his study had less disability than the 423 non-running counterparts. In fact, disability levels among the non-runners were twice those of the regular runners. Even more amazing, another study from the University of Heidelberg showed that even marathon runners didn’t have a higher risk of knee osteoarthritis than a control group of non-runners.
One thing that can cause problems for runners are injuries, particularly when they are not allowed to heal properly or don’t receive proper treatment. Common running injuries such as ankle sprains are associated with a higher risk of developing osteoarthritis, but only when the injury wasn’t allowed enough rest to heal completely. In fact, the University of Basel in Switzerland conducted a study in 2005 that revealed that chronic ankle instability leads to arthritic ankles in 70 to 80 percent of cases. Steven L. Haddad, M.D., associate professor of clinical orthopedic surgery at Northwestern University's Feinberg School of Medicine says, "Arthritis can occur because of uneven mechanics of the joint. If your joint is shifted and it's even one millimetre off, it increases the stresses placed on that joint by 42 percent. This incongruity of the surfaces leads to an erosion of cartilage."
Fortunately, most of these problems can be avoided. Taking a sensible approach to your running can prevent most injuries and lead to the protection your knees need throughout your active life. Specifically this means:
- Don’t run through the pain. If it hurts, stop and investigate the reasons for your pain. Don’t run again until the pain is gone.
- Stretch thoroughly, before and after running.
- Whenever possible, run on soft surfaces.
- Build up your running gradually and mix in plenty of rest and complementary (cross-training) activities.
- Use the best running shoes you can find. Make sure they fit you perfectly.
- Include weight training and strengthening exercises for your whole body, but particularly for the muscles and ligaments supporting the patella (kneecap), to promote stability.
- When you are injured, get proper treatment and rest. Don’t resume running too quickly.
