If you're a runner, then maybe you've worried about the long-term consequences of all that pounding on your knees. But here's some encouraging news: According to a study from Brigham Young University, running appears to reduce inflammation in the knee joint—not increase it, as commonly believed.
In fact, the authors say, running may actually protect knees down the road, and safeguard against degenerative diseases like osteoarthritis.
The new finding “flies in the face of intuition,” said study co-author Matt Seeley, PhD, associate professor of exercise science at BYU, in a press release. “This idea that long-distance running is bad for your knees might be a myth.”
To test this age-old theory, Seeley and his colleagues analyzed samples of fluid taken from the knee joints of healthy men and women, ages 18 to 35, both before and after a 30-minute run. Specifically, they measured the synovial fluid for two proteins (called GM-CSF and IL-15) that indicate the presence of harmful inflammation.
They found that levels of both proteins went down after 30 minutes of running, suggesting a decrease in overall inflammation in the joint. To rule out other factors that may have contributed to the drop, the researchers also performed a “control” test, taking fluid samples before and after a 30-minute seated rest. During that test, protein levels did not change between samples.
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The study, published in the European Journal of Applied Physiology, was very small: the researchers were only able to compare a full set of before-and-after samples for six participants. They say their findings should be confirmed in larger populations. Plus, since the participants only ran for half an hour, the same results might not apply to people logging longer distances.
Still, Robert Hyldahl, PhD, assistant professor of exercise science, believes the results are a good argument against the belief that runners are more likely to get osteoarthritis of the knee than non-runners.
Rather, they indicate that running is chrondoprotective—which means it may help delay the onset of degenerative joint diseases. “What we now know is that for young, healthy individuals, exercise creates an anti-inflammatory environment that may be beneficial in terms of long-term joint health,” Hyldahl said in the press release.
Osteoarthritis, a painful disease in which the protective cartilage between bones wears down over time, affects about 27 million people. Women are at higher risk, as are people who’ve had traumatic sports injuries. (Next, the researchers plan to study whether running’s anti-inflammatory effects also apply to people with previous knee problems, like ACL tears.)
Sedentary behavior is also a known risk factor for osteoarthritis. Strength-training and weight-bearing exercises have long been recommended to keep joints healthy, but experts have been cautious to recommend high-impact, repetitive workouts like long-distance running.
These new findings imply that, for healthy individuals, that caution may not be necessary. “This study suggests exercise can be a type of medicine,” Seeley said.
Of course, it is possible to get hurt while running—especially if you ramp up your routine too quickly or too intensely. And if you do wind up with pain and inflammation after a long run (in your knees or anywhere else), it’s important to figure out what’s going wrong so you can take steps to treat the problem.