After knee surgery, most patients experience atrophy of the quadriceps muscle, so exercising the quadriceps is an integral part of the post-operative rehabilitation process. Here are a few common methods of quadriceps training: a. Flexion of the knee position quadriceps isometric contraction, this method in the training process at different angles for the best results. Such as 30°, 60°, 90°, etc.; two, straight leg raise; three, static squat; four, seated resistance knee extension. The patient is in a seated position and the resistance is applied to the lower part of the patient’s calf; v. Supine resistance knee extension. The patient is placed in the supine position and resistance is applied to the lower part of the patient’s lower leg. Note: This method is compared with the seated resisted knee extension, the rectus femoris muscle is elongated and the contraction strength of the rectus femoris muscle is increased; vi. Supine resisted hip extension and knee extension. The patient takes a supine position, flexes the hip and knee, and applies the resistance to the plantar aspect of the foot; vii. Standing resistance knee extension. The patient is in the standing position, resistance is applied to the lower leg, and the lower leg is in the range of 90° to 180° for resistance knee extension; viii. Prone position resistance knee extension. The patient takes a prone position, bends the knee, gives resistance in the calf, and does resistance knee extension exercises; ix. Single-leg squat. X. Pedal a bicycle. Note: This method is performed postoperatively to not only strengthen the quadriceps, but also to increase joint mobility. There are many other quadriceps training methods, which are not listed here. The strength training methods for quadriceps are broadly divided into two categories: single-joint and multi-joint, subdivided into open chain, closed chain, dynamic open chain, static closed chain and many others. There have been many debates in the past about the way to train the quadriceps, and the key to the debate is which can be more beneficial for rapid recovery of the quadriceps, open-chain or closed-chain exercises. For example, the seated resistance foot knee extension is an open chain exercise, which is more targeted, but this method does not make the knee flexor muscle group get exercise, which is not conducive to the coordination of the extension and flexor muscle groups, and in the experiment it was confirmed that the resistance in the knee movement makes the tibia move forward, and the anterior cruciate ligament is in the tension position, which is not conducive to the rehabilitation of the knee joint; the static squat is a static closed chain training method, which is relatively less targeted, but in the exercise, the The extension and flexion muscle groups are exercised at the same time, which is beneficial to the stability of the joint. We can now improve the open chain training method by adding resistance to the tibial ramus, which reduces the impact on the ACL. Also, after research, the resistance only has a stretching effect on the ACL when the knee is flexed 40° to 80°, so training outside this range will not cause damage to the ACL. Therefore, the tension of the ACL depends only on the angle of the knee joint and is not related to the amount of load. As long as the stability of the joint is good, we can use single joint open chain strength training in our training. Maintaining the strength of the quadriceps muscle can be a great help in our post-operative knee recovery. When the quadriceps strength is normal, the patella slides along the normal trajectory along the femoral carriage, but after knee injury or surgery, the rapid atrophy of the medial head of the quadriceps muscle makes the tension of the lateral femoral muscle relatively increase, and during knee extension and flexion activities, the patella slides outward, increasing the pressure on the cartilage and easily aggravating the injury, so the strength of the quadriceps muscle, especially the medial head of the quadriceps, should be restored as soon as possible after knee injury. strength. Not all training methods are suitable for you, but some of them may aggravate the pain. For example, in postoperative patients with patellar strain, if the angle of resistance knee extension is not limited, it may aggravate the patellar strain and make the pain worse. Therefore, a reasonable rehabilitation under the guidance of a doctor is necessary for a better recovery.