The knee, the largest and most complex joint in the 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, with a normal human knee bearing an average of 35 kg of weight. The more weight you carry, the greater the chance of wear and tear on the joint cartilage, and the tendons are prone to injury, resulting in faster degeneration of the knee joint. According to research statistics, the weight-bearing multiples of the knee are as follows: 1. When lying down, the weight-bearing of the knee is almost zero. 2. When standing up and walking, the weight-bearing of the knee is about 1 to 2 times. 3.When going up and down slopes or up and down steps, the weight on the knee is about 3 to 4 times. 4.When running, the weight on the knee is about 4 times. 5.When playing ball, the weight of the knee is about 6 times. 6, squatting and kneeling, the weight of the knee is about 8 times. For example: a person weighing 50kg, for each step, the knees have to bear about 200kg of weight. (50 * 4 times) The human knee joint quality has 15 years of the best state: 1, 15 years old before: the knee joint is in the developmental stage, adolescent growing pains mostly occur in the vicinity of the knee joint. 2. 15-30 years old: The knee joint is in “perfect condition” and works tirelessly. As long as the knee joint tissue is not damaged, it is basically not felt. 3, 30-40 years old: patellofemoral cartilage has produced early mild wear and tear, there will be a period of vulnerability, short-term knee pain, lasting a few weeks to a few months, some people will not even notice. Patellofemoral cartilage is a 3-5 mm thick layer of hyaline cartilage in the human knee joint that cushions the knee joint from the impact of movement. However, because the patellar cartilage has no nerve distribution, it will only sound an “early warning signal” once during the vulnerable period before the full layer wears out, and strenuous exercise should be avoided during this period. From this time onwards, the knee joint can no longer be used as it pleases. 4. 40-50 years old: After walking long distances, the inside of the knee joint tends to become sore and painful, which is relieved by rubbing it with your hands. The role of the meniscus in the knee joint is to cushion vibrations and maintain stability. Since 60% of the body weight is supported by the medial side of the knee joint, degeneration of the medial meniscus occurs earlier. Because of the nerve distribution in the meniscus, people can feel soreness and pain during the degeneration process. The arrival of this phenomenon reminds people that it is time to start taking care of their joints. 5, 50 years old and above: the knee joint will feel obvious pain, this is because the “life” of the patellar cartilage has reached, the cartilage full layer wear, arthritis has been produced. This is the time to conserve the use of the joint, reduce strenuous exercise, especially stairs and climbing, and use crutches if necessary to reduce the pressure on the knee joint.