K P Granata1, A H Sanford. 1. Motion Analysis and Motor Performance Laboratory, University of Virginia, Charlottesville, Virginia 22903, USA.
Abstract
STUDY DESIGN: Low back kinematics, including relative lumbar and pelvic motions, were quantified during controlled lifting tasks. OBJECTIVES: To evaluate the influence of load and lifting velocity on lumbar-pelvic (LP) coordination. SUMMARY OF BACKGROUND DATA: Sagittal trunk extension is achieved through the coordinated motion of the pelvis and lumbar spine. There are no data to indicate whether lifting task design influences lumbar-pelvic coordination. METHODS: Lumbar and pelvic motions were recorded from 18 healthy subjects while performing isokinetic lifting tasks of 0.1 kg and 10 kg. Coordinated motions of the pelvis (sacral spine) and low-thoracic spine were evaluated using eigenvector analyses and a ratio of lumbar and pelvic angles (L/P). RESULTS: Eigenvector models of the lumbar-pelvic coordination accurately represented empirical coordination profiles. Weight significantly influenced lumbar-pelvic coordination. Trunk extension velocity demonstrated a small but statistically significant influence on lumbar-pelvic coordination. Weight and trunk flexion angle significantly influenced lumbar/pelvic angle ratios. CONCLUSIONS: Trunk extension was achieved through simultaneous but nonlinear contributions from both the pelvis and lumbar spine throughout the range of motion. The lumbar spine accounted for 70% of the total, with increased pelvic contributions in flexed postures. Task weight increased the lumbar contribution to total trunk motion. When performing clinical evaluations of spinal kinematics, it is necessary to recognize that unloaded motions may not fully represent loaded behavior of spinal coordination.
STUDY DESIGN: Low back kinematics, including relative lumbar and pelvic motions, were quantified during controlled lifting tasks. OBJECTIVES: To evaluate the influence of load and lifting velocity on lumbar-pelvic (LP) coordination. SUMMARY OF BACKGROUND DATA: Sagittal trunk extension is achieved through the coordinated motion of the pelvis and lumbar spine. There are no data to indicate whether lifting task design influences lumbar-pelvic coordination. METHODS: Lumbar and pelvic motions were recorded from 18 healthy subjects while performing isokinetic lifting tasks of 0.1 kg and 10 kg. Coordinated motions of the pelvis (sacral spine) and low-thoracic spine were evaluated using eigenvector analyses and a ratio of lumbar and pelvic angles (L/P). RESULTS: Eigenvector models of the lumbar-pelvic coordination accurately represented empirical coordination profiles. Weight significantly influenced lumbar-pelvic coordination. Trunk extension velocity demonstrated a small but statistically significant influence on lumbar-pelvic coordination. Weight and trunk flexion angle significantly influenced lumbar/pelvic angle ratios. CONCLUSIONS: Trunk extension was achieved through simultaneous but nonlinear contributions from both the pelvis and lumbar spine throughout the range of motion. The lumbar spine accounted for 70% of the total, with increased pelvic contributions in flexed postures. Task weight increased the lumbar contribution to total trunk motion. When performing clinical evaluations of spinal kinematics, it is necessary to recognize that unloaded motions may not fully represent loaded behavior of spinal coordination.