Calf pain after running can be a result of lactic acid buildup, muscle strain, or the formation of a chondroma. You can stretch the muscle properly to relieve the pain, and chondroma requires surgery. 1. Due to less running in general, the lactic acid buildup in the calf muscles caused by the sudden increase in the amount of exercise, because the lactic acid produced by anaerobic metabolism can not disappear quickly, thus causing pain. It may also be caused by muscle strain, muscle fibers will tear, resulting in muscle soreness. 2. Chondrosarcoma mostly occurs in childhood, belongs to benign bone tumor, common in lower limbs, pain can occur in the pressure on the onset. If this situation occurs, it is recommended to go to orthopedic department of regular hospital for filming and magnetic resonance to judge the treatment. In addition, it is recommended that appropriate recovery exercises, stretching muscles to gradually relieve, but also massage to promote lactic acid metabolism. Chondroma can be treated surgically.