The quadriceps is the most important muscle group of our human thighs. Firstly, it is not only responsible for our main strength when walking, walking up and down stairs, squatting and other movements, but also for the stability of our knee joints, especially the patella and the anterior-posterior stability of the knee joint. Secondly, if there is significant atrophy of the quadriceps, most commonly and most importantly the medial head (the quadriceps is divided into four heads: medial head, lateral head, middle muscle and rectus femoris), it is likely to lead to imbalances in knee balance, strength, patellofemoral stability and many other aspects of function, which can further lead to degenerative changes in the knee (like getting old early) and many other related diseases. Therefore, it is a very important thing to maintain the normal muscle state and strength of the quadriceps. Ordinary people should practice regularly to maintain the normal functions we need in our daily lives such as walking up and down stairs, squatting, etc.; people suffering from knee diseases should practice even more to enhance the protection and motor function of the knee joint, which can also promote the recovery of knee injuries. So, how do you practice? The following is a summary: First, the most common and operable is the static squat exercise, which is described in detail in my other article dedicated to the static squat, please refer to it. Secondly, it is also a very practical and easy to use leg tensing exercise. That is, when the knee is straight (sitting, standing, lying can be done) active contraction of the quadriceps muscle, so that it is tense, hold for 5 seconds, and then relax for 2 seconds, and so on. It is best to do enough 2000 times a day. It is not required to do it all at once, it can be done in several times, with the same effect. The left arrow is not needed in this picture, the right arrow points to the part that is the quadriceps (from the outer thigh), please note that the performance of this muscle group contraction is quadriceps muscle resistance exercises. Mainly the following actions: 1, straight leg lift: lying on the bed (must lie, if sitting practice, to not easy to hurt), tied a sandbag in the ankle, the weight can be determined according to their strength and feeling, no fixed requirements. General 1-3 kg can be. Straight position will lift the whole leg, so that the angle between the leg and the bed at about 30 degrees is the best. Hold for 5 seconds, then lower for 2-3 seconds, and so on. Do 3-4 sets per day, and the indicator that each set of exercises is effective is that the muscles feel fatigued enough. Then you can rest 1-2 minutes, and then repeat. 2, knee extension resistance: sitting on the edge of the bed or chair, the ankle tied sandbags. From a relaxed flexed knee position until the knee is straightened with force. Of course, the most important exercise is that the effective range of motion of the medial head is within 30 degrees of extension, so if the focus is on the medial head, the last 30 degrees is the main exercise. The exercise requires the same straight leg raise.