Soreness in calf after running may be caused by lactic acid accumulation, muscle injury, bone injury and other reasons. 1. Accumulation of lactic acid in the body: Due to the lack of exercise in daily life, the anaerobic metabolism of muscles produces lactic acid when running, and the accumulation of lactic acid stimulates the local nerves to cause soreness in the calves. 2. Muscle injury: due to excessive high-intensity exercise caused by calf muscle injury or running induced by the original muscle injury aggravation, so that the patient appears to run for a while on the symptoms of calf soreness. 3. Bone injury: due to the chronic micro-injury of bone caused by long-term running, long-term accumulation can cause fatigue fracture and other bone injuries, and the patient can have the symptom of sore calves after running for a while. There may be other reasons for the soreness of calves after running, so it is recommended to go to the hospital in time to clarify the cause of the disease and give further treatment.