Calf strains or cramps can be determined by triggers, history of trauma, and symptoms. 1. Calf muscle strain: muscle strain of the calf is very common, especially when running, jumping, leg press, splitting and sprinting, there are many chances of strain. Calf muscle strain can appear after pain, swelling, pressure pain, hardness of the injured area, calf dare not straighten and other symptoms. There is usually a clear history of trauma, and symptoms appear quickly, preventing continued activity. Usually the pain appears and worsens during the activity. 2. Calf cramp: also called muscle spasm, is a phenomenon of spontaneous tonic contraction of muscles. Calf muscle spasm is the most common, mainly caused by gastrocnemius muscle spasm, the attack can appear stiffness, soreness or severe pain. Cold stimulation of the external environment, lack of calcium, lack of sleep, excessive sweating, improper sleeping position, and fatigue can cause calf muscle spasm. In daily life, we should pay attention to keep warm, do not overwork, and be prepared for exercise so as not to cause adverse effects.