First, the muscles, tendons, ligaments and other soft tissues of the waist have been strained, mainly because the muscles are overstretched, and the pain is obvious when bending down sharply to lift heavy objects.
Second, due to strain, such as sitting for a long time, squatting for a long time, standing for a long time, and often maintaining a bent posture, the muscles of the back and the surrounding soft tissues will be in a state of fatigue, tension and strain, and inflammatory edema and pain will also occur.
Third, the muscles of the waist have spasms, mainly when the waist is cold and tired. When the waist is subjected to violent force, the muscles and surrounding soft tissues will have spasms and obvious pain.
Fourth, lumbar disc herniation, severe bending to lift heavy objects, resulting in obvious compression of the disc, rupture of the fibrous ring, and protrusion of the nucleus pulposus, which will produce local inflammation and pain.
Fifth, due to ureteral calculi, stones will stimulate the ureteral wall and cause obvious pain during the downward movement of ureter.