Spinal posture during stooped walking under vertical space constraints

Study Design. Simultaneous spine kinematic variables in sewage workers were quantified using a two-dimensional video-based gait analysis system. Objectives. To identify patterns of spinal posture in a population of sewag e workers pushing waste matter through tunnels while walking stooped under various height constraints. Summary of Background Data, Working with stooped postures is one of several occupational risk factors that have been associated with spinal disorders. However, the specific changes in spinal posture during stooped walking und er various height constraints have not been documented. Methods. A video-based Bait analysis system was used to measure spinal post ure in 22 sewage workers. Angles of the cervical, thoracic, and lumbar spin e in the sagittal plane were assessed during walking with five levels of he ight constraint, from upright walking to stooped walking under a headroom r estriction of 105 cm. Correlations among gait parameters, demographic data, and clinical results were determined. Linear regression analysis was perfo rmed to examine which variables have the largest impact on the posture resu lting from a given vertical height constraint when age and body height are held constant. Results. Mean angular values changed significantly with increasing headroom restrictions, with increases in cervical and thoracic extension as well as lumbar flexion. The cervical and thoracic angles were best correlated with height constraint, followed by lumbar angle and stride length. The inverse relation between cervical and thoracic angle during upright walking increa sed with increasing vertical space constraints, whereas the relation betwee n the thoracic and lumbar angles decreased. Subjects with decreased abdomin al muscle strength adopted a significantly more kyphotic thoracic posture w hen walking under headroom constraints than subjects with normal abdominal muscle strength. Conclusions. Combined walking and pushing under vertical space constraints was associated not only with the expected increased flexion of the lumbar s pine, but also with greater extension (i.e., reduced kyphosis) of the thora cic spine.