No. Contrary to widespread belief, running vigorously well into your later years does not raise the risk of knee osteoarthritis (swelling of the joint, with pain and stiffness, caused by wear and tear) or other disabilities. To the contrary, it can improve overall health, cutting the death rate in half, according to two new studies by Dr. James Fries, a professor of medicine at Stanford University. Both studies bolster previous research on exercise, disability, and longevity.