While running for exercise is often lauded for the fact that it aids weight loss, improves cardiovascular and respiratory health and may even help reduce the risk of developing certain cancers, it sometimes gets a bad rap for being tough on the knees. All that pounding, the thinking goes, can inflame and take its toll on the cartilage in the knee joint. A new study out of Brigham Young University, however, shows that running can actually do the opposite and ratchet down knee inflammation.

In the small study, researchers took fluid, known as synovial fluid, from the knee joints of six healthy people between the ages of 18-35 both before and after running. They looked for two inflammation markers known as GM-CSF and IL-15, which are cytokines – messenger proteins secreted by cells. Some cytokines have anti inflammatory properties but the two measured in this study have the opposite effect, causing inflammation in the body.

After the study participants ran for 30 minutes, the researchers found that levels of both GM-CSF and IL-15 had decreased in the synovial fluid, meaning that the inflammatory response was actually lowered.

"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," said study lead author Robert Hyldahl, BYU assistant professor of exercise science.

Additionally, Hyldahl added that his study revealed that rather than contributing to arthritis, as is sometimes believed, running can be considered "chondroprotective," meaning that it prevents joint-space narrowing and might delay the onset of painful and degenerative joint diseases like osteoarthritis.

"This study does not indicate that distance runners are any more likely to get osteoarthritis than any other person," Seeley said. "Instead, this study suggests exercise can be a type of medicine."

The researchers are now expanding their research to subjects with previous knee injuries. Their work has been published in the European Journal of Applied Physiology.