Thigh cramps are generally not a precursor to serious illness, but may indicate a calcium deficiency, sacroiliitis, lumbar disc herniation and other diseases, and may also be caused by overwork. 1. Calcium deficiency: Calcium can maintain the excitability of skeletal muscle cells and promote muscle contraction. If there is a calcium deficiency in the body, the concentration of calcium ions in the body will decrease, thus affecting the generation of action potentials in the skeletal muscles, leading to repeated contraction of the skeletal muscles and the phenomenon of thigh cramps. 2. Sacroiliac arthritis: due to excessive fatigue and chronic strain, aseptic inflammation occurs in the local muscles, ligaments, joints and other tissues of sacroiliac joints, and the aggravation of inflammation will cause muscle spasm or muscle atrophy, resulting in cramps in the thigh muscles. 3. Herniated lumbar intervertebral disc: after the degenerative changes of lumbar intervertebral disc, it will compress the nerves around the lumbar vertebrae, which will cause sensory abnormality and dysfunction in the innervated area, and thus cause the phenomenon of thigh cramps. 4. Excessive exertion: such as participating in strenuous physical activities, sweating too much, resulting in electrolyte imbalance, can also lead to cramps. Do not be alarmed when thigh cramps occur, if they occur frequently or are difficult to relieve, it is recommended to go to the hospital in time for a comprehensive examination, a clear diagnosis and then follow the doctor’s instructions for treatment.