Bending suddenly thumped may be the lumbar spine normal popping, small joint disorders and other physiological causes, may also be due to osteoporosis, lumbar intervertebral disc herniation and other pathologic causes. 1. Physiological reasons: normal joints around the joint cavity exists, there is a negative pressure inside the joint cavity so that the joint surfaces fit, the middle walk joint fluid for lubrication, when the joint movement, the external force exceeds the negative pressure in the joint cavity, the gas inside the joint cavity is extruded, rupture, the joints of physiological popping. In addition, when the intervertebral small joint dysfunction, there may also be staccato when bending over. 2. Pathological reasons: when the lumbar vertebrae and their surrounding soft tissues are diseased, it may also lead to the occurrence of the above situation, such as lumbar vertebrae degenerative disease leading to lumbar intervertebral disc protrusion, osteoporosis in the elderly, and so on. Pathological causes will lead to the appearance of intervertebral bone, soft tissue damage, bone brittleness and other manifestations, which in turn lead to the stability of the entire vertebrae decreased, appearing when bending over the thumping symptoms. If the symptoms of stooping and thumping are not relieved or are accompanied by other symptoms, the patient should go to the hospital in time for consultation and targeted treatment after clarifying the cause.