The arm is not red, not swollen, and it hurts when you move it, which may be due to the lack of warmth and cold, or it may be due to lesions in the upper limb neuromuscular, joints, and ligaments such as tenosynovitis, synovitis, and tennis elbow. 1. Cold: a cold arm causes poor local blood flow, which leads to lactic acid and other metabolites can not be discharged in a timely manner, thus triggering pain. 2. Tenosynovitis: When the joints move, the tendons and tendon sheaths rub against each other too much, which will cause inflammation, and the redness and swelling may not be obvious at the beginning, but when the tendon sheaths rub against each other after the movement, the pain will be generated. 3. Synovitis: Synovitis is an aseptic inflammation caused by irritation of the synovial membrane. Synovitis may not show redness and swelling at the beginning, but if the secretion fluid accumulates locally, the joint will gradually swell up. 4. Tennis elbow: This is a muscle and tendon strain caused by frequent flexion and extension of the elbow joint. Redness and swelling are not obvious, and pain is obvious when you move. The arm is not red and not swollen, but continued pain in activities, should seek medical attention in time to avoid delaying the condition.