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Lumbar-pelvic range and coordination during lifting tasks.

Authors
Maduri-A; Pearson-BL; Wilson-SE
Source
J Electromyogr Kinesiol 2008 Oct; 18(5):807-814
NIOSHTIC No.
20034692
Abstract
Spine motion has been described to have two regions, a neutral zone where lumbar rotation can occur with little resistance and an elastic zone where structures such as ligaments, facet joints and intervertebral disks resist rotation. In vivo, the passive musculature can contribute to further limiting the functional neutral range of lumbar motion. Movement out of this functional neutral range could potentially put greater loads on these structures. In this study, the range of lumbar curvature rotation was examined in twelve healthy, untrained volunteers at four torso inclination angles. The lumbar curvature during straight-leg lifting tasks was then defined as a percentage of this range of possible lumbar curvatures. Subjects were found to remain neutrally oriented during the flexion phase of a lifting task. During the extension phase of the lifting task, however, subjects were found to assume a more kyphotic posture, approaching the edge of the functional range of motion. This was found to be most pronounced for heavy lifting tasks. By allowing the lumbar curvature to go into a highly kyphotic posture, subjects may be taking advantage of stretch-shortening behavior in extensor musculature and associated tendons to reduce the energy required to raise the torso. Such a kyphotic posture during extension, however, may put excessive loading on the elastic structures of the spine and torso musculature increasing the risk of injury.
Keywords
Musculoskeletal-system; Musculoskeletal-system-disorders; Posture; Ergonomics; Motion-studies; Back-injuries; Injury-prevention; Risk-factors; Author Keywords: Lumbar spine; Lifting; Manual materials handling
Contact
S.E. Wilson, Human Motion Control Laboratory, Department of Mechanical Engineering, University of Kansas, 3138 Learned Hall, 1530 W. 15th Street, Lawrence, KS 66045
CODEN
JEKIE3
Publication Date
20081001
Document Type
Journal Article
Email Address
sewilson@ku.edu
Fiscal Year
2009
NTIS Accession No.
NTIS Price
Issue of Publication
5
ISSN
1050-6411
NIOSH Division
HELD
Source Name
Journal of Electromyography and Kinesiology
State
WV; MO
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