The Effect of Posture on the Strength of the Lumbar Spine

Abstract

Experiments were performed on cadaveric lumbar intervertebral joints in order to assess the effects of heavy lifting on the lumbar spine. It was found that in the simulated erect lordotic posture, the apophyseal joints can resist a significant proportion of the intervertebral compressive force. Slightly flexed lumbar joints have a compressive strength that comfortably exceeds the forces generated by heavy lifting. Hyperflexion just beyond the normal limit of motion can render lumbar intervertebral discs vulnerable to posterior prolapse when compressed by physiological loads. It is concluded that no injury should be sustained by the osteoligamentous lumbar spine as a result of a single heavy lift provided that the lumbar spine is kept slightly flexed.