Thighs appear sore, weakness, caused by the following reasons: 1, due to the patient to carry out long-distance walking, or high-intensity sports, for mountain climbing exercise. This leads to the metabolism of the legs, a large accumulation of lactic acid, failure to timely decomposition and triggered by the appearance of soreness, weakness. 2, due to wind and cold stimulation of the legs, or excessive force on the muscles of the legs, and triggered by the appearance of thighs soreness, weakness. 3, due to some diseases, such as nerve compression in the legs, sciatic nerve compression in the buttocks, lumbar disc herniation compression of the nerve roots, resulting in patients appear Soreness and weakness of the legs.