In recent years, people pay more and more attention to their health. Running has become people's first choice, which not only saves time, but also improves physical fitness. Running is not limited by location and space, so it is more convenient and faster. Regular jogging can achieve the effect of reducing fat and weight, and effectively increase athletes' muscle strength and cardiopulmonary function. However, improper running strength and posture will do harm to athletes. According to related reports, nearly half of people have different degrees of pain after running. The research shows that running is one of the most serious items that lead to the injury of individual skeletal muscle system in all fitness exercises.

First, the causes of knee joint injury during exercise

(1) Structural factors of knee joint

Some studies have pointed out that knee joint injury has little to do with athletes' age and gender [5]. One of the most important factors is the structure of the knee joint. There are tibial collateral ligament and fibular collateral ligament on the lateral and medial sides of the knee joint. Among them, the cruciate ligament in the knee joint has a restraining effect, and the knee joint cavity contains synovial fluid and meniscus, which is an important part of human walking. The main reason why the knee joint of runners is easily injured is that the knee joint plays a role in relieving the impact force during running.

(2) The influence of running posture

Most athletes have cartilage injury, but the knee joint injury of the general population is more serious due to the influence of running posture [7]. Athletes need to drive the muscles and joints of the whole body to move together when running, and the running posture can transfer all the buffering force to the corresponding joints. However, the incorrect running posture will lead to the athlete's inability to better grasp the strength when running, which will lead to the knee joint being damaged by more force, such as the wrong landing action of the lower limbs and the wrong swing of the hip joint.

Second, preventive measures to reduce knee injuries

(1) Stick to the correct running posture.

When running, athletes need to maintain the correct posture to reduce the probability of joint injury. Good running posture can further relieve the strength of athletes' knees. An important part of all running processes is the athlete's footwork. Ordinary runners can choose to roll their heels to the forefoot first, while professional runners often use the method of tiptoe landing, which they think can bring more running impact to their bodies. Some studies have pointed out that athletes who run with both feet on the ground have stronger cushioning ability, lower load on ankle and hip joints, and the endurance of athletes' knee joints is obviously increased.

(2) improve physical fitness

Strengthening physical fitness can reduce the injury of runners to the knee joint. Gradually strengthen the leg muscle strength, the most important is tensor fascia lata and quadriceps femoris. Strengthening quadriceps femoris can reduce the impact on meniscus and patella during running. The main practice methods are squatting against the wall, squatting, squatting and climbing stairs. And pay attention to strengthening the core muscle groups of the body, and constantly train and improve muscle strength.