Soreness in the left arm is commonly caused by left arm muscle strain, periarthritis and cervical spondylosis, as follows: 1. Left arm muscle strain, prolonged maintenance of a fixed position or overweight, resulting in muscle strain of the left upper limb, which will be manifested as soreness and swelling of the left arm, accompanied by a sense of weakness, massage, physiotherapy, hot compresses will bring rapid relief of clinical symptoms; 2. Patients suffering from periarthritis of the shoulder joint and cervical spondylosis will manifest symptoms of left arm soreness, mainly related to limited mobility of the shoulder joint and neurological symptoms. Patients suffering from periarthritis of the shoulder and cervical spondylosis will show symptoms of left arm pain, which is mainly related to the restricted movement of the shoulder joint and the radiological symptoms of the nerves. By means of manipulative relaxation therapy and cervical traction and braking therapy, the symptoms of left arm pain can be gradually relieved or even completely disappeared. Early diagnosis and early treatment are conducive to the relief of left arm pain symptoms. Delayed treatment may worsen the symptoms of left arm pain and may lead to muscle atrophy and weakness of the left arm, therefore, if left arm pain occurs, it is important to pay attention to it and consult a doctor in time.