Maybe you (like the editor of this blog), have been advised by your doctor or trainer to stay away from running if you want to avoid arthritis of the knee. But two research studies, published in July and September in Medicine and Science in Sports and Exercise, suggest that this advice is more myth than good science.
The authors conclude that running does not increase the risk of osteoarthritis of the knee or hip. In fact, they conclude the opposite; that running is the sort of exercise that helps thicken the cartilage of the knee, and thus helps protect the joint from long-term damage.
The study published in July, from the Lawrence Berkeley National Laboratory, recruited over 75,000 runners as part of the National Runners’ and Walkers’ Health Studies, which ran from 1991 to 2002.
Their overall conclusion was “no evidence that running increases the risk of osteoarthritis, including participation in marathons.” And even though it sounds like it goes against logic, they found the rate of arthritis in serious walkers was almost twice as high as the rate in runners. The researchers believed this is because people who run tend to be thinner, and that being overweight places harmful forces on the knee cartilage.
In the second study, just published in September, titled “Why Don’t Most Runners Get Knee Osteoarthritis?”, Canadian and American researchers compared the amount of weight or force applied to the knee of runners vs. walkers.
They found that runners produced about three times more force for each stride taken, but that the impact time for runners was much shorter than for the walkers, and that the runners had fewer number of impacts (since the strides were longer for runners). The net result of these various factors was that running and walking produced approximately the same overall force to the knee over an equivalent distance.
Dr. Ross Miller, one of the researchers, notes that knee cartilage seems to benefit from rhythmic and forward motion like running, whcih seems to stimulate cartilage cells to divide and replenish. So a certain amount of stress, applied in the correct way, makes the knee cartilage stronger. It is a similar concept to weight lifting. When you stress the muscle tissue, you causes the muscle cells to grow and become stronger.
Science journalist Alex Hutchinson, author of a Runner’s World blog, says “People think the joint is just a static, inert hinge that wears down, but it’s actually a dynamic, living thing that can respond to stress and adapt and get stronger”.
More important factors for developing knee arthritis are family history and obesity. Family history you cannot control, but obesity is treatable. Another important cause of knee arthritis is trauma, which can occur from running but more likely from contact sports, or sports that require sudden changes in direction. Tendon or ligament injuries create joint scar tissue which can cause abnormal joint strains and osteoarthritis later on.
Now these studies do not mean that if you have been sitting on the couch you can just get up and start running long distances. And particularly if you already have had knee problems or injuries, you should talk to a doctor—preferably a sports medicine specialist— before you start to run. But the research is good news for most of us, and we don’t need to fear running.
See also in ProcuraMed:
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