If the patient has pain when going down to the waist, it may be caused by the following reasons: first, it may be caused by lumbar spine instability, some patients may be due to the lumbar arch root isthmus fracture, followed by the existence of lumbar vertebral body slippage, at this time the patient will have lumbar spine instability. This type of patients in the bending or excessive back stretching waist, it is possible to aggravate the instability, and will also cause related nerve irritation, at this time there will be low back pain. Secondly, it may be caused by acute lumbar sprain. If the patient suffers from acute lumbar sprain, it will cause the patient to keep the lumbar area in a semi-straight state continuously. Once the patient is asked to bend over, it will stimulate the injured muscles, which will then lead to pain. Thirdly, it is common for patients to suffer from lumbar disc herniation, which causes the herniated disc to produce more serious stimulation to the nerve root once the patient bends down, and then causes low back pain.