The stiffness of the thigh muscles may be caused by the following reasons: 1. prolonged standing or prolonged sitting in daily life, infrequent physical exercise and induced stiffness. 2. strain of the quadriceps muscle in the thigh area, resulting in local swelling and inflammatory edema, resulting in muscle tightness after injury, easily inducing muscle stiffness and tightness. 3. The muscle stiffness of the thigh is caused by the stimulation of wind and cold, due to muscle spasm and local blood circulation failure. You can massage the muscles in the thigh area, you can massage and knead from the legs upwards in order to relax the stiff muscles and promote blood circulation.