To protect the knee joint in daily life, middle-aged and elderly people should pay attention to keeping warm and avoiding wind and cold; combine work and rest; maintain proper weight to reduce the weight on the knee joint; and maintain proper standing and sitting posture. Before exercise, choose a flat place to train; wear comfortable shoes and clothes, knee pads and other protective gear; and perform gentle warm-up exercises. When exercising, the range of motion of the joints should not cause pain, and the movement should be even and slow; there should be no obvious fatigue after exercise; the amount of exercise should be increased gradually; functional exercise should be consistent. After exercise, relaxation exercises should be performed. Note: Avoid turning, jumping and other impact movements during exercise to reduce joint wear; extreme joint activities, such as strong squatting positions in yoga, are prohibited. Perform functional exercises Strength exercises Weighted straight leg raise exercise: supine position, lift the leg straight up 30 to 45 degrees. Weighted knee extension exercise: in the seated position, lift the lower leg upward as much as possible flush with the thigh. Weighted knee flexion exercises: in the standing position, lift the lower leg backwards, 60 to 90 degrees from the thigh, with the thigh perpendicular to the ground. Ankle exercises: stand holding the wall and lift both heels up. Each movement is held for 15-30 seconds, and both legs repeat the exercise. 10 times as a group, 2-3 groups per day. Tie 2 to 3 kg sandbags around the ankles when carrying weight. Flexibility exercises calf exercises: face the wall, hands on the wall, the upper body is straight, a leg back extension 60 ~ 90 cm, the palm of the foot completely on the ground, toes facing forward. Put the weight on the front leg and straighten the back leg. Thigh exercises: face the wall, stand on the right foot, hold the wall with the right hand. Lift your left foot and use your left hand to grab your ankle and pull it to your hip while pressing your thigh forward. Each movement is held for 15-30 seconds, and both legs repeat the exercise. 10 times as a group, 2 to 3 groups per day.