The knee, the largest and most complex joint in the human body, is a hinge joint, and it is one of the few joints in our body that can only move in one direction. The knee is also the largest weight-bearing joint in the human body, and the average weight-bearing capacity of a normal person’s knee is 35 kilograms. The more weight you bear, the greater the chance of wear and tear of the articular cartilage, and the tendons are also prone to injury, and the knee joint degenerates faster. The weight-bearing capacity of the knee is as follows: 1) When lying down, the weight-bearing capacity of the knee is almost 0. 2) When standing up and walking, the weight-bearing capacity of the knee is about 1~2 times. 3) When going up and downhill or up and down steps, the weight-bearing capacity of the knee is about 3~4 times. 4) When running, the weight-bearing capacity of the knee is about 4 times. 5) When playing soccer, the weight-bearing capacity of the knee is about 6 times. 6) When squatting and kneeling, the weight-bearing capacity of the knee is about 8 times. 7) When kneeling, the weight-bearing capacity of the knee is about 6 times. 8) The weight-bearing capacity of the knee is about 10 times. The weight on the knees is about 8 times as much when squatting and kneeling. For example, for a person weighing 50kg, every time he goes up a step, his knees have to bear about 200kg of weight. Human knee joint quality has 15 years of the best state before 15 years old: knee joint in the development stage, puberty growing pains occurred in the knee joint. From 15 to 30 years old: The knee joint is in a “perfect state” and works tirelessly. As long as it doesn’t damage the knee joint tissues, you basically can’t feel its existence. 30~40 years old: The patellar cartilage has early and mild wear and tear, and there will be a period of vulnerability, with short-term knee pain that lasts for a few weeks to a few months, and some people may not even be aware of it. The patellofemoral cartilage is a 3 to 5 millimeter thick layer of transparent cartilage in the human knee joint that cushions the knee from the impact of movement. But because the patellar cartilage has no nerve distribution, so in the whole layer before the wear and tear will only be in the fragile period of pulling a “warning signal”, in this period to avoid strenuous exercise. From this time onwards, you can no longer use your knee as you wish. Age 40-50: After walking long distances, the inner side of the knee tends to become sore, which can be relieved by gently rubbing it with your hands. In the knee joint, the meniscus serves to cushion vibrations and maintain stability. Since 60% of the body’s weight is supported by the inside of the knee, degeneration of the medial meniscus occurs earlier. And because there are nerves in the meniscus, one can feel the soreness during the degeneration process. The arrival of this phenomenon reminds people that it is time to start taking care of their joints. Above 50 years old: the knee joint will feel obvious pain, this is because the patellar cartilage “service life” has come to the cartilage of the whole layer of the causes of knee pain in the elderly.