Posterior calf tendon pain may be caused by physiological factors, but also may be a symptom of certain diseases, such as knee, osteoarthritis, lumbar spine compression of the nerve, etc., should be timely consultation to identify the cause. 1. Physiological factors: Consider the strain caused by the previous day’s excessive exercise or overwork, can cause the symptoms of calf pain in the posterior hamstring. 2. Pathologic factors (1) Knee joint, osteoarthritis: mainly occurs in the elderly, will appear behind the knee joint discomfort, feel like tendon pain. Because some old people will have cysts of periosteum after osteoarthritis, that is, the synovial fluid leaks out to the back of the knee joint, which may cause compression of the local tissues and cause pain. (2) Lumbar spine compression of nerves: It is possible that the lumbar spine compresses the nerves, which can also cause pain in the back of the calf. In addition to the above factors, there may be other reasons, it is recommended to go to the hospital as soon as possible for examination, the doctor to clarify the cause of the disease, and then give targeted treatment.