The pain in the middle of the upper arm may be caused by muscle strain, osteochondritis, cervical spondylosis and so on. 1. Muscle strain: in the case of insufficient preparatory activities, weak muscle extension, incorrect posture, etc., sharp contraction or excessive pulling of muscles during exercise may cause muscle strain of the upper arm, the patient may experience severe pain in the upper arm, can be touched with the muscle of the striated hard lumps, localized swelling, and activity is obviously restricted and other symptoms. 2. Osteochondritis Dissecans: It is a kind of periosteal injury with the manifestation of periosteal and periosteal blood vessel expansion, congestion, periosteal hyperplasia and inflammatory changes, etc. It can be caused by septic infection or periosteal pulling and tearing injury during exercise, and the patients can have pain, edema and activity obstacles in the inflammation part of the upper arm, and some of the lesions can cause generalized pain and chills. 3. Cervical spondylosis: it is a general term for a group of cervical spine diseases, including hyperplastic cervical spondylitis, cervical nerve root syndrome, cervical disc herniation, etc. It is related to ageing, long-term strain and other factors. If the lesion injures the spinal nerve root, it can cause pain and movement disorders in its innervated parts, such as the upper limbs. Patients with pain in the middle of the upper arm need to undergo relevant examinations before the specific cause can be clarified and appropriate treatment can be carried out. In addition, it is necessary to pay attention to the preparatory activities before exercise and daily behavioral posture to protect the spine and muscles to avoid the occurrence of the disease.