The phenomenon of collapse of the posterior side of the waist, that is, the concave line of the waist is very obvious, may be due to the state of anterior tilt of the pelvis. The sacral and caudal vertebrae are the posterior walls of the pelvis, and when the overall horizontal position of the pelvis tilts forward, the sacral and caudal vertebrae will also tilt forward, causing the lower lumbar vertebrae to gradually tilt forward, which will cause the entire posterior lumbar region to collapse. Because of the pelvic tilt lumbar collapse symptoms of people, generally can not be a long time to lie down supine posture rest, once a long time lying down supine will make the waist appear sore, painful feeling. Some people are often fitness people, especially the low back muscles and hip muscle training people, will make the low back muscles and hip muscles often in a state of tension, will also pull the entire lumbar spine collapse phenomenon.