The causes of arm with chest pain include physiological and pathological ones. Pathological arm with chest pain may be caused by frozen shoulder, tendonitis and other reasons. 1. Physiological factors: it may be inappropriate exercise methods, too strong exercise amplitude, resulting in increased anaerobic metabolism, resulting in lactic acid accumulation, which leads to muscle pain, at this time, after appropriate rest, the symptoms can be relieved. 2. Pathological factors (1) Frozen shoulder: Frozen shoulder is caused by self-limited aseptic inflammation of the soft tissues around the shoulder joint for unknown reasons. Frozen shoulder is usually characterized by pain around the shoulder joint, inability to raise the arm, and pain at the joint between the arm and the chest. (2) Tendonitis: Tendonitis is a wear and tear of the fibrous tissues outside the tendon due to overuse and repetitive pulling caused by frequent movement of the joint over a long period of time. Tendonitis is usually characterized by numbness, stiffness, swelling and pain at the arm and chest joints. Patients are advised to go to the hospital if they have pain in the arm-chest joint position and the symptoms cannot be relieved after rest.