Causes of arm soreness include fatigue, inflammation of the shoulder joint, radicular cervical spondylosis, and lateral epicondylitis of the humerus. 1.. Fatigue: Being in the same position or using the same action for a long time leads to fatigue of the hand muscles thus causing soreness and swelling in the arm. It can be relieved by hot compresses, rest and activities. 2. Inflammation of shoulder joint: such as frozen shoulder can cause arm soreness. 3. Neurogenic cervical spondylosis: compression and stimulation of the cervical nerves affects the normal conduction of the nerves, resulting in soreness, pain, numbness and other symptoms in the hands. 4. Epicondylitis of the humerus: long-term throwing, rotating movements or lifting heavy objects. It can cause epicondylitis of the humerus, which triggers arm soreness and swelling. Arm soreness may also have other reasons, it is recommended to go to the hospital in a timely manner to improve the examination, to clarify the cause of the disease, to give targeted treatment or treatment.