1, linkage. When running, if the strength of upper limbs and shoulder straps is weak, it can't match the strength needed for running of lower limbs. The muscles of the upper limbs and shoulders have to bear more loads than usual, so it is not surprising that the muscles of the shoulders are sore.

2. flexibility. If the flexibility of the shoulder joint or the range of joint motion is not good enough, it will inevitably affect the range of the swing arm. If the flexibility of the shoulder muscles is not good, it will increase the burden on the muscles that normally participate in the swing. If it takes a long time, it will also cause muscle and soft tissue injury and overuse, thus causing pain.

3. Poor running posture. If you can't keep a good posture of your spine when running, such as the habitual posture of bowing your head, holding your chest and bending over, it will cause local muscle imbalance in your shoulders, neck, chest and back. Some muscles are overburdened, some muscles are too tense, and some are in a shortened state, which is not conducive to the normal function of muscles and will cause pain over time.

4. The technical movements of running are not standardized. When running, if the shoulders can't be relaxed and supported, the neck and shoulder muscles that shouldn't be stressed continuously will be in a state of constant tension and stress. Running in this posture will easily lead to shoulder and neck pain and even strain.

Second: How to relieve shoulder stiffness when running?

Slow down or just walk. Look forward, turn your head 45 degrees to the right, then hang your head forward and try to put your ears close to your chest. Raise your left hand and press and massage your left shoulder. Massage dozens of times, massage the right shoulder dozens of times as usual, and press it for a while if necessary, which can effectively relieve shoulder pain.

Third: How to prevent shoulder pain when running?

1, strengthening muscle strength is an important means to reduce shoulder and neck muscle injury. Especially, we should pay attention to exercise and stabilize the rotator cuff muscles of the shoulder joint, so that the shoulder joint can maintain a stable state when moving in all directions.

2. While carrying out strength training, don't neglect the flexibility exercise of shoulder and neck, especially the range of motion of shoulder joint internal and external rotation and backward extension.

3, always pay attention to keep the body up, chest and abdomen running posture, keep the straight line of the spine, and the straight line relationship between the trunk and the back kick. It is best to ask a special running coach to help you correct and improve your running skills.