After ACL reconstruction, early training is very important for postoperative rehabilitation. Generally, rehabilitation training can be started when the anesthesia subsides. Among the rehabilitation exercises that need to be performed immediately after surgery are: 1. Ankle pump exercises: hook the toe upward with maximum force for 5 seconds and then step downward for 5 seconds, several times a day. This action can effectively prevent postoperative thrombosis. 2, quadriceps contraction training: commonly known as tensing. Patients contract the anterior thigh muscles for 5 seconds and then relax for 2 seconds, several times a day. This training can effectively prevent muscle atrophy and have a lifting effect on the patella to prevent joint adhesions. 3. Straight leg raising exercise: If the pain allows, it can be started on the day after surgery; if the patient cannot tolerate the pain, it can be performed on the 2nd-3rd day after surgery, but no later than 3 days. The so-called straight leg raise exercise is to lift the knee straight up 30 degrees from the bed, about 375px, and continue until exhaustion. Both ankle pump exercises, quadriceps contraction exercises and straight leg raise exercises are muscle strength exercises. Although they are intense, they are not very painful for the patient. The real headache for the patient is the joint mobility exercises. Joint mobility exercises: they are flexion and extension exercises, and the common method is to bend the leg. Because of the fear of pain, many patients are afraid to try leg bending exercises, resulting in slow progress. It is important to know that slow progress can cause joint adhesions, and adhesions can greatly affect joint function, which may require massage or even joint adhesion release. If no leg bending exercises are performed at all and the adhesions are allowed to develop, 2-3 months after surgery, the adhesions in the knee joint will be like 520 glue and will be completely unbreakable, and the patient will feel even more pain at that time. In the early postoperative period, when the joint has just been glued together, it can be easily broken apart with leg bending exercises. Therefore, it is important to start joint mobility exercises early as it is better to have pain later than earlier. Although joint mobility exercises need to be started early, they do not need to be excessive and intense. Generally speaking, leg bending exercises are allowed only once a day, or even once every two days, and it is recommended that each exercise should not exceed 15 minutes. While muscle strength exercises emphasize multiple exercises per day, the more practice muscle strength recovery the better. But leg bending exercises are different, too much practice will lead to swelling and pain in the joints, and then the joints will become stiff and less and less mobile. In short, joint mobility training needs to be done as early as possible, but it should not be over-stimulated. As for whether the joint mobility exercises will break the ligaments, this is not a concern for patients at all. The tendons are fixed very securely during surgery, and the flexion and extension exercises do not affect the ligaments and tendons much. However, it is worth noting that if adhesions have already occurred and you wait until six months after surgery to break them, then not only the ligaments may break, but also the bones may be fractured, which needs to be handled by a professional doctor.