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Evidence for an exposure-response relationship between trunk flexion and impairments in trunk postural control.

Authors
Hendershot-BD; Toosizadeh-N; Muslim-K; Madigan-ML; Nussbaum-MA
Source
J Biomech 2013 Sep; 46(14):2554-2557
NIOSHTIC No.
20044053
Abstract
Prolonged trunk flexion alters passive and active trunk tissue behaviors, and exposure-response relationships between the magnitude of trunk flexion exposure and changes in these behaviors have been reported. This study assessed whether similar exposure-response relationships exist between such exposures and impairments in trunk postural control. Twelve participants (6 M, 6 F) were exposed to three distinct trunk flexion conditions (and a no-flexion control condition), involving different flexion durations with/without an external load, and which induced differing levels of passive tissue creep. Trunk postural control was assessed prior to and immediately following trunk flexion exposures, and during 10 min of standing recovery, by tracking center of pressure (COP) movements during a seated balance task. All COP-based sway measures increased following each flexion exposure. In the anteroposterior direction, these increases were larger with increasing exposure magnitude, whereas such a relationship was not evident for mediolateral sway measures. All measures were fully recovered following 10 min of standing. The present results provide evidence for an exposure-response relationship between trunk flexion exposures and impairments in trunk postural control; specifically, larger impairments following increased exposures (i.e., longer flexion duration and presence of external load). Such impairments in trunk postural control may result from some combination of reduced passive trunk stiffness and altered/delayed trunk reflex responses, and are generally consistent with prior evidence of exposure-dependent alterations in trunk mechanical and neuromuscular behaviors assessed using positional trunk perturbations. Such evidence suggests potential mechanistic pathways through which trunk flexion exposures may contribute to low-back injury risk.
Keywords
Humans; Men; Women; Posture; Musculoskeletal-system; Body-weight; Body-mechanics; Body-distribution; Exposure-levels; Physical-fitness; Physical-reactions; Physiological-effects; Physiological-factors; Physiology; Author Keywords: Creep deformation; Exposure-response; Low back pain; Postural control; Trunk flexion
CODEN
JBMCB5
Publication Date
20130927
Document Type
Journal Article
Funding Type
Grant
Fiscal Year
2013
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-008504
Issue of Publication
14
ISSN
0021-9290
Source Name
Journal of Biomechanics
State
VA
Performing Organization
Virginia Polytechnic Institute and State University
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