Leg cramps, also known as muscle spasms, are a symptom of sudden tightening and pain in the leg muscles. The common causes are prolonged strenuous exercise, calcium deficiency, lumbar disc herniation and so on. 1. After a long period of strenuous exercise: the leg muscles are in a state of continuous contraction, causing the leg muscles to spasm due to fatigue. 2. Calcium deficiency: Calcium deficiency will increase the excitability of the nerves, leading to muscle dysfunction, causing the muscles to become easily excited and muscle spasms. Clinically, leg cramps occur. 3. Herniated lumbar intervertebral disc: the protruding nucleus pulposus compresses and stimulates the nerve root, leading to abnormalities in the muscles innervated by the nerve root of the lower limb, resulting in leg cramps. There may be other causes of leg cramps, such as cold stimulation, exertion, etc. It is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and standardized treatment under the guidance of the doctor.