Calf belly hard may be muscle development and other physiological factors, may also be local fasciitis, neuropathy, tumor lesions and other pathological factors. 1. Physiological factors: common in the long-term fitness or long-term running crowd, muscle development, or excessive exercise caused by local muscle spasms, can be caused by the calf touch can feel the feeling of hardness. 2. Local fasciitis: chronic aseptic inflammation of local muscles caused by long-term strain injury can stimulate local muscle spasm, thus causing stiffness and pain in the calf. 3. Neuropathy: lumbar spine lesions cause secondary changes in the nerves of the lower limbs, which stimulate the calf muscles and cause contraction and spasm of the calf muscles, thus producing a stiff sensation. 4. Tumor lesions: such as calf soft tissue tumors or bone tumors, especially malignant tumors such as sarcoma of rhabdomyosarcoma, chondrosarcoma, etc., which can cause local swelling and hardness. Calf belly hardness may have other reasons, it is recommended to go to the hospital in a timely manner to improve the relevant examination, to clarify the cause of the disease and then give further treatment.