Calf cramps may be related to calcium deficiency, strenuous exercise and ischemia of muscle tissue. 1. Calcium deficiency: If the intake of calcium is too low or the loss of calcium is too high, it will often cause hypocalcemia, in which the concentration of calcium ions in the blood is low, which may lead to an increase in the tension of the muscle tissues, thus resulting in the appearance of cramps in the calves. 2. Strenuous exercise: in the process of strenuous exercise, the calf muscles will continue to contract, which may lead to spasm of the muscle tissues, and there will be symptoms of calf cramps. 3. Muscle tissue ischemia: calf veins appear phlebitis, sclerosis, varicose veins and other pathological changes, often affect the blood supply of local muscle tissue, resulting in ischemic spasms of muscle tissue, calf cramps will occur. Causes of calf cramps more reasons, usually need to avoid overwork, and pay attention to leg warmth, but also actively supplement calcium, if the symptoms of calf cramps continue to aggravate, you need to consult a doctor in time for examination.