How Running Helps Your Knees

What if everything they told us about running and knees was wrong? That’s what New York Times fitness writer Gretchen Reynolds suggests, based on research at Brigham Young University, where scientists drew blood and synovial fluid (the stuff the lubricates joints) from 30 healthy volunteers before and after they either ran for 30 minutes or sat for 30 minutes. Reynolds reports that the researchers focused on substance known as cartilage oligomeric matrix protein, or COMP, which accumulates in diseased knees and is often used as a marker of arthritis. Here’s what they found: the knees of runners had far less of two types of cells that can contribute to inflammation, and the runners had more COMP in their blood and less in their synovial fluid. Why? The researchers think that running squeezes the COMP out of the knee and into the blood, making knees healthier, not less healthy.