The lumbar spine consists of five vertebrae (L1-L5), which continue upward to the thoracic spine and downward to the upper pelvis, where they are associated with the sacrum. The five vertebrae increase in size sequentially downward and are the most mobile (flexion and extension oriented) spinal segments after the cervical spine, while the lumbar spine is also subject to forces from the weight of the trunk itself and from muscle contraction. Therefore, the lumbar spine is also the site of most skeletal diseases, such as overexertion-induced lumbago and disc herniation. Therefore, in ordinary work, life to protect the lumbar spine, the specific should do the following: stand with a station “phase” when the human body stands, the line of gravity of the trunk will pass vertically through the center of the fourth vertebral body ventral (both front side), so that the spine has been subjected to forward flexion (bending) moment (this moment is equal to the upper body weight W and its If we do not pay attention to body posture at this time, always bend forward (such as chest), the line of gravity then moved forward, further increasing the bending moment, while the body in order to maintain the trunk upright state, the vertical spinal muscles (behind the superficial and relatively thick two muscles) and other deep muscles on the dorsal side of the spine (behind) will be in a continuous state of activity, over time, the muscles will appear strain and cause pain. In addition, the body bends forward will cause the disc front and back stretch pressure increases, eventually leading to the nucleus pulposus to move backward, will greatly increase the risk of lumbar disc herniation, so usually work and study to try to maintain an upright and upright state, stand as “pine” is not without reason. The torso gravitational line in the standing position The bending moment at the lumbar spine when the torso is flexed forward