Stiff calf muscles may be related to physiological reasons such as long-term exercise, as well as pathological reasons such as muscle strain and lumbar disc herniation. 1. Physiological reasons: there may be some physiological reasons, such as long-term exercise, resulting in the local calf muscle is more developed and stiffness, usually long-term running or playing soccer and other strenuous exercise crowd, or do fitness exercise crowd. If there is no localized pain, there is no need for special treatment. 2. Pathological causes (1) Muscle strain: muscle strain caused by prolonged standing work or physical activities can cause symptoms of calf muscle stiffness. (2) Lumbar disc herniation: it may be due to lumbar disc herniation, so that the nerve root of the lower limb is compressed, thus causing calf muscle stiffness. Calf muscle stiffness may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.