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Disturbance and recovery of trunk mechanical and neuromuscular behaviors following repeated static trunk flexion: influences of duration and duty cycle on creep-induced effects.

Authors
Muslim-K; Bazrgari-B; Hendershot-B; Toosizadeh-N; Nussbaum-MA; Madigan-ML
Source
Appl Ergon 2013 Jul; 44(4):643-651
NIOSHTIC No.
20043376
Abstract
Occupations involving frequent trunk flexion are associated with a higher incidence of low back pain. To investigate the effects of repeated static flexion on trunk behaviors, 12 participants completed six combinations of three static flexion durations (1, 2, and 4 min), and two flexion duty cycles (33% and 50%). Trunk mechanical and neuromuscular behaviors were obtained pre- and post-exposure and during recovery using sudden perturbations. A longer duration of static flexion and a higher duty cycle increased the magnitude of decrements in intrinsic stiffness. Increasing duty cycle caused larger decreases in reflexive muscle responses, and females had substantially larger decreases in reflexive responses following exposure. Patterns of recovery for intrinsic trunk stiffness and reflexive responses were consistent across conditions and genders, and none of these measures returned to pre-exposure values after 20 min of recovery. Reflexive responses may not provide a compensatory mechanism to offset decreases in intrinsic trunk stiffness following repetitive static trunk flexion. A prolonged recovery duration may lead to trunk instability and a higher risk of low back injury.
Keywords
Musculoskeletal-system-disorders; Repetitive-work; Humans; Men; Women; Biomechanics; Body-mechanics; Motion-studies; Muscle-function; Muscle-physiology; Physiological-function; Physiological-measurements; Body-regions; Back-injuries; Neuromuscular-function; Neuromuscular-system; Work-intervals; Reflexes; Ergonomics; Electrophysiological-effects; Physiopathology; Author Keywords: Low back pain; Biomechanics; Creep deformation; Trunk flexion; Stiffness; Reflex; Gender
Contact
Maury A. Nussbaum, Department of Industrial and Systems Engineering, Virginia Tech, 250 Durham Hall (0118), Blacksburg, VA 24061, USA
CODEN
AERGBW
Publication Date
20130701
Document Type
Journal Article
Email Address
nussbaum@vt.edu
Funding Type
Grant
Fiscal Year
2013
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-008504; M112013
Issue of Publication
4
ISSN
0003-6870
Source Name
Applied Ergonomics
State
VA; KY
Performing Organization
Virginia Polytechnic Institute and State University
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