The stiffness of the thigh muscles may be caused by the following reasons: 1, excessive exercise, such as patients for the thighs to do excessive fitness exercise, due to excessive muscle fatigue, may cause internal muscle edema, will make the thigh area of the muscle very stiff. 2, the thigh area of pain, such as serious trauma to the thigh area, or due to lumbar disc protrusion, in this area to produce serious radiation If the patient has a high level of neuronal injury, such as cervical cord injury, or cerebral hemorrhage or cerebral infarction, then the patient will have very high muscle tone in the lower limbs for a long time. 4. The soft tissue contusion, fracture, in its recovery process, there is a large amount of calcium salt deposits inside the muscle, which in turn leads to very stiff muscles.