Reviews compiled and written by Chase
Ergonomics, Inc.
©1996 Chase Ergonomics, Inc.
Reproduction prohibited without express
written permission from Chase Ergonomics, Inc.
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Overview of Recent Back Support Studies
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Does a Lifting Belt Reduce the Spine Moments During Sudden
Unexpected Loading?
*Lavender, S.A., **Shakeel, K., *Andersson, G.B.J., **Thomas,
J.S.+
*Department of Orthopedic Surgery, Rush-Presbyterian-St. Luke's
Medical Center, Chicago, IL.
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Introduction: Several occupational factors have been
explored as to their contribution to low back disorders (LBDs).
In many cases the onset of back pain stems from an unanticipated
loading that occurs during the material handling task, for example;
when lifted objects stick together, when a multiple person lift
fails, when preventing an accident, or during a loss of footing
(slip).
The biomechanical consequences of these sudden unexpected loads
have been investigated as sudden loads were applied to the torso
via the hands, and via direct application to the torso. In all
studies the unexpected sudden loads led to increased loading
of the spine and its supporting tissues. In part this occurs
because of the destabilizing effects of the agitation and in
part, there may be an over-reaction to the unforseen event.
The following specific hypotheses were tested:
- A lifitng belt reduces the trunk motion in the sagittal,
frontal and transverse planes following unexpected sudden loading.
- A lifting belt reduces the peak dynamic external moments
acting on the spine during sudden unexpected loading.
Methods: Ten males and eight females participated in
a randomized sequence of unexpected loading trials. Variables
were tightened and untightened supports and straight-on versus
45-degree asymmetric applied loads.
Results: The forward bending motion of the torso was
significantly reduced with the tightened support during the straight-on
loadings. The lateral flexion of the spine was significantly
reduced in both symmetric and asymmetric loadings with a tensioned
back support. The twisting motions in the spine were unaffected
by the support. Significant decreases in the forward flexion
moments at the spine and the right hip occurred only in the male
subjects.
Discussion: This study provides evidence that back
supports stiffened the torso through the reduction in the sagittal
plane motion. This study showed that a tensioned back support
reduced the forward bending in all subjects and the forward bending
moments in males. A limitation of this study was the need to
restrict the loads applied (7.5% of each subject's maximum trunk
extension strength) so that the subjects' safety would not be
compromised.
Quote: "One can only speculate as to the benefits
of a lifting belt during an unexpected loading event of larger
magnitude."
Study presented at the 45th Annual Meeting of the Orthopaedic
Research Society, February 1999, Anaheim, California.
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