Who knew? An on-line article from Time/CNN recently reported on several studies that counter the long-held belief that running is bad on the joints and leads to early osteoarthritis (OA) of the knee.

OA is frequently explained as simple “wear and tear” on a joint in which the   cartilage that covers the joint, erodes leading to painful joint destruction. Given the pressure exerted on the knee joint (up to 4x body weight during walking and 8x while running), it was logical to assume that runners would exhibit greater rates of OA of the knees than non-runners.

A study done at Stanford University and published in the Archives of Internal Medicine  in 2008 followed approximately 1000 runners and non-runners over a 21 year period. At the conclusion of the study, runners and non-runners had the same rate of OA and in fact, runners had a 39% lower mortality rate than non-runners.

So what contributes to OA? Genes and certain risk factors (some modifiable and some not) like obesity and aging. Obesity more than doubles the risk of developing OA of the knee and OA is more common in adults over 65 (and more common in women).

So why is it that the enormous stress placed on the joint doesn’t cause OA? According to the lead researcher of the Stanford study, Dr. James Fries, “When you bear weight, (the joint) squishes out fluid and when you release weight it sucks in fluid.” This confers a protective benefit to the joint and may lead to a thicker, healthier knee cartilage.

You can read more about this research and other studies by following this link to the TIME/CNN on-line article. Or better still, head outside for a quick 3 mile run…..