Many older people who develop arthritis invariably do very little activity, and some patients have been counseled on whether they should be less active as they age in order to protect their joints. Clinically, prolonged bed rest and braking of the joints can lead to stiffness and further joint damage. In fact, moderate activity level exercise in middle-aged and elderly patients does not increase the risk of osteoarthritis, and even patients with anatomical or biomechanical abnormalities or those who already have early osteoarthritis are able to benefit from regular exercise. However, proper estimation of joint structure and function is essential before starting an exercise program. These patients should choose exercises (e.g., exercises in water) that place low loads on the joints and maintain joint motion while increasing muscle strength. Exercises that cause collisional and torsional forces on the joints should be avoided. This is because these exercises can make severe osteoarthritis progressively worse. For patients with mild to moderate osteoarthritis, a well-designed exercise program can increase the mobility of the affected joints, increase the muscle strength of the whole body, and enhance the patient’s mobility. The exercise program should include three aspects: flexion and extension exercises to increase joint mobility, training to increase muscle strength, and aerobic exercises to increase tolerance and reduce fatigue. Improvements in the preoperative condition of the surgical patient will significantly improve the postoperative outcome.