The knee is the largest and most complex joint in the human body. The knee joint is the largest weight-bearing joint in the human body, and a normal human knee joint can carry 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 and faster degeneration of the knee joint. The relationship between knee weight bearing and body position When lying down, the knee weight bearing is almost zero; when standing up and walking, the knee weight bearing is about 1-2 times; when walking up and down slopes or stairs, the knee weight bearing is about 3-4 times; when running, the knee weight bearing is about 4 times; when playing ball, the knee weight bearing is about 6 times; when squatting When squatting and kneeling, the knee is about 8 times heavier. Before the age of 15, the knee joint is in a developmental stage, and most of the growing pains of adolescence occur near the knee joint; between the ages of 15 and 30, the knee joint is in “perfect condition” and works tirelessly. As long as the knee tissue is not damaged, its presence is basically not felt; 30-40 years old, the patellofemoral cartilage has early mild wear and tear, and a period of weakness occurs, with short-term knee pain lasting a few weeks to a few months, which some people do not even notice. Patellofemoral cartilage is a 3-5 mm thick layer of hyaline cartilage in the knee joint that cushions the knee joint from sports; however, because patellofemoral cartilage has no nerve distribution, it will only sound a “warning signal” during the vulnerable period before the full layer wears out. During this period, it is important to avoid strenuous exercise. This is also the time when the knee joint can no longer be used as you wish. Between the ages of 40 and 50, the medial side of the knee tends to become sore after walking long distances, which is relieved by gentle rubbing. In the knee joint, the meniscus is used to cushion vibrations and maintain stability; 60% of the body’s weight is supported by the medial side of the knee joint, so 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. This phenomenon is a reminder that it is time to start taking care of your joints. Over the age of 50, the knee joint will feel significant pain because the patellar cartilage has reached the end of its “useful life”, the cartilage is worn down and arthritis has developed. 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. Daily care for sore knees 1. Don’t walk for too long and rest immediately when your knees feel uncomfortable; 2. Don’t do heavy exercise, such as running, high jumping and long jumping; 3. Avoid half squatting, full squatting or kneeling positions, such as squatting horse stance; 4. Don’t do half flexion rotation of the knee to prevent half plate injury; 5. Maintain ideal weight to reduce the burden on the knees; 6. 6, pay attention to the warmth of the knee, you can wear long pants, knee pads to protect the knee; 7, less heavy lifting, less high-heeled shoes; 8, avoid trauma and overwork; 9, the choice of shoes is very important. A pair of shoes that fit you can not only make you walk comfortably, but also reduce the impact and pressure on the knees during exercise; 10, the instep part of the foot can be closely combined with the shoe, the width and length are appropriate, and can correctly maintain the arches of the foot; 11, the weight of the shoe to light, the sole should not be too soft, and a little thickness; 12, the heel of the shoe can be about 2-3 cm high, the sole is too flat when walking easily fatigue; 13, shoes with non-slip pattern on the sole. Knee muscle strength, stability training Side lying exercises Lie on your left side, knees slightly bent, heels together. Head on the left arm, eyes straight ahead, then abdominal tense, hip tense, try to lift the right leg of the knee, lift the leg when the body does not move, adhere to a few seconds, put down. Repeat the exercise 15 times, change legs. Leg lift exercise Stand behind a solid bench or step, step on your right foot (heel not overhanging) and focus your weight on your right foot, raise your body and touch your left toes to the step, hold for 1 to 5 seconds. Then lower the left foot and tap the ground. Repeat 8 to 10 times, switching legs. Bridge exercise Lie flat on the ground with knees bent and feet hip-width apart, arms at your sides. Slowly lift the hips and smoothly off the ground. Then slowly lower. Repeat 15 times. Leg extensions Lie flat on your back with knees bent and feet flat on the floor. Extend the left leg, put in a stretching strap or towel, and grab the ends of the strap with both hands. Use the strap to pull the leg toward the chest, and then force the calf straight, holding it for 10 to 30 seconds to exercise the calf muscles and hamstrings. Repeat the movement 3 to 5 times, then switch legs.