Physical activity. Light or moderate physical activity and exercise that do not cause pain or injury do not increase the risk of OA.18Female runners and tennis players are three times more likely to develop tibiofemoral and patellofemoral knee OA than are age-matched controls.19 The risk of developing OA of the shoulder is increased by participation in overhead sports activities, while OA of the elbow is associated with weight lifting and sports involving throwing. Other joints can also be affected by OA, and significant trauma or injury to those joints is frequently a major factor. Examples include the ankle and foot in ballet dancers, the shoulder after rotator cuff injury, and the metacarpophalangeal joints in workers using jackhammers.17, 20, 21