A variety of muscle strength exercises should be performed early after knee surgery to reduce muscle atrophy and promote recovery. Some common muscle strength exercises are described below. First quadriceps static contraction (isometric contraction): If it is not a problem with the knee extension device (e.g. patellar tendon rupture, patellar fracture or quadriceps tendon rupture), then a large number of quadriceps static contractions should be performed the day after surgery. Usually 5 seconds of contraction and 2 seconds of relaxation is one contraction, for a total of 500-1000 reps per day. Second straight and lateral leg lifts: However, if the leg lift is not completely straight, you should start again with quadriceps static contraction, otherwise it can be dangerous, especially after ACL reconstruction, straight leg lifts that are not straight can easily cause anterior fork laxity. The leg lift usually insists on each time to exhaustion, then down to rest a few dozen seconds before the next time, about 30 times a day at each angle. The third static squat: early static squat to lean against the wall, so more stable, the point is that the feet are shoulder-width apart, toes naturally forward, the knee joint is put right not inside the buckle, the knee joint can not exceed the toes, chest up, do not hold your breath. For safety, you can also put a bench under your buttocks. Again, each time to squat to exhaustion, usually most people can squat 1-2 minutes. Usually 10 times a group, 2-3 groups per day. Some people may squat to a certain angle more painful then change an angle squat, such as 60 degrees pain, then change to 70 degrees or 50 degrees squat. The increased muscle strength will protect the joints, thus reducing the risk of re-injury. However, plyometric exercises are also relatively tedious and somewhat painful, some patients will give up halfway, then the future function of the joint will not be too good, in order to be able to return to life back to the field, we still have to cheer hard to practice plyometric!