Many people worry that running ruins knees. But a new study finds that the activity may in fact benefit the joint, changing the biochemical environment inside the knee in ways that could help keep it working smoothly.
In my many decades as a runner, fellow runners and nonrunners alike have frequently told me that I am putting my knees at risk. The widespread argument generally follows the lines that running will slowly wear away the cartilage that cushions the bones in the joint and cause arthritis.
But there is little evidence to support the idea, and a growing body of research that suggests the reverse. Epidemiological studies of long-term runners show that they generally are less likely to develop osteoarthritis in the knees than people of the same age who do not run.
Some scientists have speculated that running may protect knees because it also often is associated with relatively low body mass. Carrying less weight is known to reduce the risk for knee arthritis.[..] findings suggest that a single half-hour session of running changes the interior of the knee, reducing inflammation and lessening levels of a marker of arthritis, says Robert Hyldahl, a professor of exercise science at B.Y.U. and lead author of the study, published in the European Journal of Applied Physiology. // But sitting for 30 minutes also changed the knee, he points out, which he and his colleagues had not expected. Sitting seemed to make the knee biochemically more vulnerable to later disease.
Dr. Hyldahl noted that this was a very small and short-term study. He and his colleagues would like to repeat it with much larger numbers, “once we figure out how to get more synovial fluid” safely from healthy knees, he says. // They also hope to study longer running distances and different paces, to see how those variables affect changes within the knee, and to recruit older and injured runners, whose knees might have begun to respond fundamentally differently to the activity than the joints of healthy people in their 20s. // But even with these limitations, the findings suggest that moderate amounts of running are “not likely to harm healthy knees and probably offer protection” against joint damage, Dr. Hyldahl says.