It is common to see some middle-aged and elderly people doing functional knee exercises, they repeatedly flex and extend the knee joint, rub the patella for a while, and shake the knee joint for a while. This is because most middle-aged and elderly people have degenerative changes in the knee joint, such as degeneration of the articular cartilage and osteophytes, which manifest as knee pain, quadriceps atrophy, increased pain when going up and down stairs, inability to stand up on their own after squatting, or even fluid in the knee cavity and contracture deformity of the flexed knee. The purpose of functional exercises for this type of knee joint is to reduce quadriceps atrophy and to reduce and eliminate knee joint pain. Flexion and extension of the knee joint, rubbing the patella and shaking the knee joint cause the patellar cartilage to repeatedly rub against the cartilage surface of the femoral condyles, which increases cartilage wear and tear, resulting in increased knee pain and even joint effusion, which in turn aggravates muscle atrophy, which in turn aggravates the original symptoms, forming a vicious circle. The correct way to practice the knee joint should be as follows: straighten the knee joint as much as possible, practice the contraction of the quadriceps muscle while keeping the knee straight, each contraction should be insisted on 3-4 seconds, 10 times per minute, and 5-10 minutes per hour. The medial head of the quadriceps can also be selectively stimulated with an electrical stimulator if available, to make the medial femoral muscle strong and powerful, to reduce pain and prevent quadriceps atrophy. In addition to this, excessive knee movement should be avoided, and the use of a toilet seat should be applied.