Many middle-aged and elderly people have this feeling: going up and down the stairs with weak legs, accompanied by knee pain, especially in a semi-squatting position when the pain is unbearable, which is likely to be osteoarthritis in play. To a certain extent, although osteoarthritis is painful in the joints, the root of the disease is in the cartilage. The normal knee joint has a thin layer of cartilage, which is like a “lubricant” between the bone and the bone, without its protection, the bones will grind the bone when walking, which is very painful due to the abundance of nerves and blood vessels in the periosteum. In the long run, the knee joint will grow bone spurs and even become deformed. Cartilage is a dense, gelatinous substance that is not only stronger but also more flexible than bone. As adults, we have cartilage in the joint surfaces of the bones, intervertebral discs, auricles, rib cartilage and even the trachea, which play an important role in the body in bearing loads and reducing friction between bones in the joints. In addition to osteoarthritis, rheumatoid arthritis, lumbar disc herniation, meniscus injury, rheumatoid arthritis and other joint diseases, although the etiology is different, but most of the “pain in the joint, the disease in the cartilage”, through X-ray or MRI, you can see the patient’s joint cartilage wear, tear, etc.. Unfortunately, once cartilage is damaged, it has little ability to regenerate. After the age of 30, the cartilage’s ability to extend and restore its original shape begins to weaken, and the reduction in joint fluid dries out the joint cartilage, so when people reach a certain age, the joint cartilage is prone to damage, wear and tear, and degenerative arthritis. In general, some cartilage can repair itself to a certain extent, but even if it does, it is not as wear-resistant as normal cartilage and can be easily damaged again. If it develops to a more serious degree, joint replacement is required. Therefore, in life, we must pay attention to the protection of cartilage. Moderate exercise “nourish” cartilage. When the joints move, the cartilage compresses and relaxes with each other, so it can absorb nutrients and discharge waste like a sponge, making it easier for long-term inactivity to degenerate. However, inappropriate or excessive exercise can cause excessive load on the joints. The best exercise is swimming, but also brisk walking, cycling and other non-weight-bearing or less weight-bearing exercises. Avoid weight-bearing to reduce stress. It is important to avoid activities that repeatedly flex and extend the knee joint under weight, such as hiking, climbing, squatting, etc. If knee pain or enlargement occurs, be sure to take more rest and avoid strenuous exercise and prolonged squatting. Eat more cruciferous vegetables. Eat more cruciferous vegetables such as cabbage, broccoli and radish, which are rich in organic sulfides that strengthen the ligaments and increase the secretion of joint lubricating mucus. In addition, eat less high-fat and high-sugar foods and control your weight to reduce pressure on the knee joint.