The tendon pain at the back of the leg may be caused by physiological factors such as prolonged exercise, or it may be caused by pathologic factors such as calcium deficiency, venous embolism of the lower extremities, tendonitis, and so on. 1. Physiological reasons: due to prolonged playing ball, running and other sports, the leg muscles are overloaded, resulting in excessive metabolic products in the body, lactic acid accumulation in the legs, the phenomenon of hamstring pain at the back of the leg will occur, which is a normal physiological phenomenon, and the symptoms can be relieved by themselves after resting. 2. Pathological causes (1) Calcium deficiency: due to the lack of calcium, hypocalcemia can occur, the main symptom is neuromuscular symptoms, numbness of the hands and feet, or even muscle pain, severe twitching of the hands and feet can occur. Therefore, the tendon pain at the back of the leg may also occur. (2) Lower extremity venous embolism: due to lower extremity venous embolism, when the body carries out normal activities, blood circulation may be impaired, resulting in ischemia and hypoxia of blood vessels in the legs, so the phenomenon of tendon pain at the back of the leg may occur. (3) Tendonitis: chronic strain injury due to long-term exercise and other chronic strain injury can cause aseptic inflammation of tendons and surrounding soft tissues, resulting in tendonitis, which is mainly manifested as pain at the site of localized injury, and tendon pain at the back of the leg will occur when inflammation occurs in the tendons of the calf. When the patient appears behind the leg tendon pain phenomenon, it is recommended that the patient as soon as possible to consult a doctor for examination, identify the cause of the disease and follow the doctor’s instructions for targeted treatment.