Cramps can be caused by calcium deficiency, insufficient blood supply and muscle spasm. 1. Calcium deficiency: If there is hypocalcemia, it will cause abnormal excitation of nerves, which will induce leg cramps after straining the leg. Calcium tablets and vitamin D should be supplemented appropriately. 2. Insufficient blood supply: If the blood supply to the legs is not good, the legs will cause further vascular constriction and ischemia after straining, which will lead to leg cramps. Local massage, hot compresses or physical therapy can be used to promote blood circulation. 3. Muscle spasms: If the leg muscles are tensed for a long time, the muscles will remain tense and cause spasms in the leg muscles. Reverse stretching can relieve muscle spasm. It is recommended that patients go to the hospital for examination to clarify the cause of the disease and take appropriate measures under the guidance of the doctor.