Pain in the posterior thigh tendon may be caused by physiological reasons such as excessive exercise and insufficient rest, or it may be caused by pathological factors such as pyriformis syndrome and lumbar spine disease. 1. Physiological reasons: there are several myofascial tissues attached to the posterior thigh, such as the large adductor muscle and hamstring muscle, if the usual amount of exercise is relatively large or insufficient rest after exercise, it may cause aseptic inflammation or acute strains in the soft tissue area of the posterior thigh, resulting in metabolite buildup or myofascial tear, and the symptom of pain in the posterior thigh tendon appears. 2. Pathological factors: the sciatic nerve is responsible for innervating the sensation and movement of the posterior thigh, if the sciatic nerve is stimulated by compression or pulling due to various reasons, the above symptoms may also occur, possibly due to the pyriformis muscle injury of the pyriformis muscle syndrome; it may also be due to the lumbar spinal cord herniation, spinal stenosis and other lumbar spinal cord diseases caused by the nerve compression. The symptoms of pain at the back of the thigh tendon alone sometimes can not accurately determine the cause, but also need to be combined with the characteristics of the medical history, other test results to make an accurate judgment, it is recommended to clarify the cause of the disease under the guidance of a doctor.