Thigh muscle pain and weakness is commonly caused by the following reasons: First, heavy physical labor or squatting and other fitness actions, thigh muscle strain and muscle fiber tears, can cause muscle pain and weakness, the reason is that the thigh muscle in the inflammatory changes that occur after the strain, weight-bearing squatting can cause thigh muscle fibers to occur in a subtle tear, which ultimately leads to the occurrence of pain in the thigh muscle and weakness symptoms; Second, thigh Muscle by trauma direct violence, can cause thigh muscle injury, such as car accidents, ultimately causing thigh muscle swelling, pain, intra-muscular hemorrhage, the muscle can not be normal force, the treatment includes thigh muscle rest, braking, physical therapy, after treatment of pain symptoms and weakness symptoms can be relieved.