Running for a long time, chest pain, is due to the fork in the air, the cause of the fork in the air is caused by respiratory muscle spasm, the performance of septal muscle and intercostal muscle spasm, the patient will appear in the chest as well as bilateral pain in the arch of the ribs. The main reason is due to the lack of effective warm-up before strenuous activities, that is, not all the muscles of the whole body are mobilized, in strenuous activities, the muscles of the limbs, including skeletal muscles, will consume a lot of nutrients and blood, and at the same time, it will cause the abdominal muscles, respiratory muscles, transient ischemia and hypoxia, which is manifested as respiratory muscle spasm. Therefore, it is recommended to warm up before strenuous activities and mobilize all the muscles of the body before running.