It is a popular belief that the wear and tear of running causes osteoarthritis of the knees and other joints. Doctors now know this is not true. According to exercise scientist Paul Williams, studies show quite the opposite.  Williams heads up the National Runner’s Health Study as well as the National Walkers’ Health Study. These projects have followed close to 90,000 runners and walkers since their inception in 1991 and 1997, respectively. An analysis of these studies was published in the journal Medicine & Science in Sports & Exercise. Williams studied the rates of osteoarthritis and hip replacements of the participants and found that runners were only half as likely to develop osteoarthritis or need a hip replacement as walkers. Running actually strengthens joints and is associated with a lower BMI (body mass index), keeping you stronger and healthier. Recreational running benefits the knees and hips, in addition to overall health. Only 3.5% of runners develop hip or knee arthritis. A sedentary lifestyle increases the risk of hip or knee arthritis by 10.2% to 13.3%.  On the other hand, one point of caution is needed. These findings do not mean that people who have arthritis should take up running. Running with pre-existing arthritis can actually worsen symptoms. Exercise is an important part of treating osteoarthritis, but that exercise must be professionally prescribed to be safe and effective. Always check with a physical therapist or health care provider before starting any exercise program.  Williams P. Effects of running and walking on osteoarthritis and hip replacement risk. Medicine & Science in Sports & Exercise. July 2013; 45(7): 1292-1297.  Alentorn-Geli et al, “The Association of Recreational and Competitive Running With Hip and Knee Osteoarthritis: A Systematic Review and Meta-analysis” (J Orthop Sports Phys Ther 2017;47(6):373–390. doi:10.2519/jospt.2017.7137).