Sore buttocks to thighs may be caused by lactic acid accumulation, lumbar disc herniation or pyriformis syndrome, etc., which need to be examined before the cause can be clarified. 1. Lactic acid accumulation: After the hip and leg muscles have not been exercised for a long time, sudden and prolonged strenuous exercise, exceeding the limit of aerobic exercise, can lead to lactic acid can not be decomposed and accumulate in the muscles, causing the symptoms of soreness from the buttocks to the thigh muscles. 2. Herniated lumbar intervertebral disc: After degenerative changes occur in various parts of the lumbar intervertebral disc, the fibrous annulus of the intervertebral disc ruptures due to external factors and the nucleus pulposus protrudes out to compress and stimulate the spinal nerve root, causing pain in the lumbar back and radiating pain from the buttocks to the thighs, and other symptoms. 3. Piriformis syndrome: Hip sprain or hip injury can cause piriformis syndrome, stimulating the sciatic nerve, which can lead to pain in the buttocks and around the hip joint, the pain can radiate to the lower limbs, and the pain worsens after walking. Buttock to thigh pain symptoms can also be caused by other factors such as femoral head necrosis, if the patient’s symptoms can not be relieved, you need to go to the hospital for relevant examinations and treatment, to avoid affecting the patient’s quality of life.