Thigh pain after exercise, the most common are the following reasons: 1, may be after strenuous exercise leads to the production of lactic acid, lactic acid accumulation in the thigh root of the muscle near the stimulation of the muscle and the emergence of localized soreness, usually rest for two or three days this situation will naturally get better. 2, it may be the root of the thigh muscles and ligament strain, usually do not warm up enough or exercise suddenly move too strenuously and muscle, ligament strain. 3, if it is after exercise thigh pain, along with the usual often have thigh pain, it is necessary to pay attention to whether there are thigh pain, ligament strain. When the movement is suddenly too strenuous and muscle, ligament strain. 3, if it is after the movement of the thigh root pain, along with the usual often have thigh root pain, we must pay attention to whether there is hip arthritis, or even the possibility of aseptic necrosis of the femoral head. This situation generally must go to the hospital to check the local X-ray film or MRI, basically can be diagnosed.