Effects on spinal posture of varying loads pushed while walking at different gait velocities

Pushing activities are associated with a considerable risk for back disorders. Previous findings verify that pushing tasks influence trunk position, but do not establish how spinal posture and curvature change when pushing while walking. There is no information about how changes in spinal curvature are influenced by the load being pushed and the velocity at which it is pushed.

Purpose of this study was therefore to evaluate the effect on spinal posture of varying loads during the sustained phase of pushing activities while walking at different velocities.

21 male and 9 female healthy subjects took part in the study. Video rasterstereography was used to measure trunk inclination, pelvic tilt, and spinal curvature in the sagittal, frontal and transverse planes. During measurements, subjects walked with constant velocity (either 3 km/h or 5 km/h) while pushing different loads (0 N, 80 N or 160 N).

The results indicate that the magnitude of the load pushed significantly affects (p < 0.01) the trunk forward inclination, the pelvic tilt and the curvature of the spine in the sagittal plane. As the load pushed increases, the kyphotic angle decreases while the lordotic angle remains unchanged. Kyphosis apex increases and lordosis apex decreases. This effect is independent of gait velocity and gait phase.

Our findings suggest that pushing activities may primarily alter the curvature of the thoracic spine and influence the transition between the lumbar and thoracic spine. This could be worth considering when thinking about the load on the spine during pushing tasks.