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Lavender S. (1), Andersson G.B.J. (2), Corcos D.2 and
Thomas J. (2)
(1) Rush-Presbyterian-St. Luke's Medical Center, Chicago,
IL
(2) University of Chicago, Chicago, IL
Introduction: When unexpected mechanical loading of the spine
occurs because of a shifting load, or even a change in footing
or a stumble, a back injury can be the result. Since lifting
belts have been shown to limit lateral bending and twisting in
the torso, it was hypothesized that stiffening of the torso by
a belt would reduce compensatory muscle forces during an unanticipated
loading event.
Method: In this study, 20 subjects experienced eight different
laboratory combinations, each performed three times, which involved
sagittally symmetric and asymmetric suddenly-applied bending
movements both expected and unexpected (through use of a blindfold),
and with a lifting belt worn tensioned or extremely loose. The
bending movements were applied through a weight and pulley system
and an apparatus that restrained the pelvis. Electromyographic
(EMG) data were obtained bilaterally from four back muscle groups.
Conclusions: During sagittally symmetric applied movements,
both expected and unexpected, EMG response was relatively unaffected
by use of the lifting belt. However, the belt did reduce the
Erector Spinae EMG during unexpected asymmetrical loading to
a level close to that during non-blindfolded symmetrical applied
movements.
"The results suggest that individuals working in
environments where slipping is likely, or where materials frequently
shift when handled, may derive some benefit from the lifting
belt, although additional research is needed for individuals
in unconstrained postures."
Steven A. Lavender, PhD
Study results presented at the American Industrial Hygiene
Conference and Exposition, May 1996, Washington DC.
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