The most common factors are the following: 1, the most common factor is muscle overwork, or muscle release too much lactic acid and caused by excessive exercise or exercise without attention to the way and method, lactic acid accumulation in the body, especially in the more developed skeletal muscle thighs, there will be local hardness, local stiffness of clinical symptoms and conditions. 2, leg infection such as leg infection cellulitis or by The lymph nodes at the root of the thigh will become stiff. 3, when there is cerebrovascular disease, there will be stiffness and numbness in the thighs, mobility disorders, etc.