Osteoarthritis of the knee is a common disease in middle-aged and elderly patients. There are many treatment methods available, medications, joint cavity injections, joint cavity irrigation, arthroscopy, joint replacement, etc. However, one of the most important issues that many patients overlook, and the one that we instruct patients about the most in the clinic, is the issue of knee muscle training. Muscles are the barrier and protection of the joints, and strong muscles are effective in avoiding damage to the joints and reducing the occurrence of joint degeneration. Therefore, you will understand why the incidence of knee osteoarthritis is less in men than in women. Therefore, training of the knee muscles must be given attention because it is the basis of treatment and is the most important treatment. Let’s start by understanding the muscles around the knee joint. The knee muscles include the quadriceps in the front, the N cord in the back and the gastrocnemius. the N cord is located at the back of the thigh and consists of the biceps femoris, semitendinosus and semimembranosus. The long head of the biceps femoris muscle starts at the sciatic tuberosity, the short head starts at the lower lateral lip of the femoral ridge, and the biceps tendon ends at the small head of the fibula; the semitendinosus and semimembranosus muscles also start at the sciatic tuberosity and end at the proximal medial side of the tibia. The main function is to flex the calf and extend the thigh, and the N muscle corresponds to the powerful quadriceps. The quadriceps muscle is composed of the rectus femoris, medial femoris, lateral femoris, and middle femoris muscles. The tendons of the four muscles converge together to become the quadriceps tendon, which ends at the tibial tuberosity downward as the patellar tendon and is an important part of the knee extension device.