| Summary: | Study Design. This study investigated the effects of a lumbar support belt on lumbar disc deformation and joint angles. Trunk strength and endurance were also compared to disc deformation and joint angles to determine if any meaningful relationships existed.
Objective. The purpose of this study was to determine if back support belts relieve stresses encountered by the lumbar spine during lifting activities and thus reduce the risk of injury. Additionally, trunk strength and endurance measures were collected in order to determine if strong, well conditioned trunk musculature aids in the support of the lumbar spine.
Summary of Background Data. Low-back pain and injury are responsible for a major portion of lost work days and injury compensation claims. Back support belts have been proposed as a counter measure towards reducing low-back injuries in the industrial setting.
Methods. Twelve male subjects (average age, 49.7 years) performed two sessions of stoop type lifting with a loaded milk crate (11.5 kg), at a rate of 4 repetitions per minute, for a total 15 minutes per session in accordance with the NIOSH 1993 lifting
equation. The order of testing with and without a belt was randomized for the two
sessions. Fluoroscopic images were collected prior to and following both lifting sessions.
Fluoroscopic images were collected with the subjects positioned at the initiation (flexed
trunk), mid-range, and completion of the lift (erect standing). Images were imported into
Auto Cad where lumbar disc deformation and joint angles were measured by calculating
changes in position of adjacent vertebra (L3-4 and L4-5). A reduction of deformation was
deemed indicative of reduced stress. Trunk extension and flexion strength were measured
with a Kin Com isokinetic dynamometer. Trunk flexion endurance was measured via a 60
second curl-up test.
Results. Analysis of variance revealed that compressive and shear disc deformation were reduced while in the erect trunk posture for the support belt condition (p<.05). No significant reduction in disc deformation was detected while in flexed trunk postures for the support belt condition (p>.05). A significant inverse relationship was detected (p<05) between: abdominal strength and shear stress (flexed trunk positions), abdominal endurance and shear stress (erect trunk), and spinal erector strength and L4-L5
joint angle (erect trunk).
Conclusions. During stoop type lifting, support belts provide a measurable amount of stress reduction of the lumbar spine when the trunk is in the erect posture, with little effect during flexed trunk positions. Strong, well conditioned trunk musculature is associated with reduced stress on the lumbar spine. === Graduation date: 1998
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