Details:

Alternative Title:
PLoS One
Publisher's site:
http://dx.doi.org/10.1371/journal.pone.0048625
Personal Author:
Toosizadeh, Nima ; Nussbaum, Maury A. ; Bazrgari, Babak ; Madigan, Michael L.
Toosizadeh, Nima ; Nussbaum, Maury A. ; Bazrgari, Babak ; Madigan, Michael L. Less -
Description:
Experimental studies suggest that prolonged trunk flexion reduces passive support of the spine. To understand alterations of the synergy between active and passive tissues following such loadings, several studies have assessed the time-dependent behavior of passive tissues including those within spinal motion segments and muscles. Yet, there remain limitations regarding load-relaxation of the lumbar spine in response to flexion exposures and the influence of different flexion angles. Ten healthy participants were exposed for 16 min to each of five magnitudes of lumbar flexion specified relative to individual flexion-relaxation angles (i.e., 30, 40, 60, 80, and 100%), during which lumbar flexion angle and trunk moment were recorded. Outcome measures were initial trunk moment, moment drop, parameters of four viscoelastic models (i.e., Standard Linear Solid model, the Prony Series, Schapery's Theory, and the Modified Superposition Method), and changes in neutral zone and viscoelastic state following exposure. There were significant effects of flexion angle on initial moment, moment drop, changes in normalized neutral zone, and some parameters of the Standard Linear Solid model. Initial moment, moment drop, and changes in normalized neutral zone increased exponentially with flexion angle. Kelvin-solid models produced better predictions of temporal behaviors. Observed responses to trunk flexion suggest nonlinearity in viscoelastic properties, and which likely reflected viscoelastic behaviors of spinal (lumbar) motion segments. Flexion-induced changes in viscous properties and neutral zone imply an increase in internal loads and perhaps increased risk of low back disorders. Kelvin-solid models, especially the Prony Series model appeared to be more effective at modeling load-relaxation of the trunk.
Subject:
[+]
Adult Biology Biomechanical Phenomena Elasticity Female Humans Lumbar Vertebrae Male Medicine Models, Biological Movement Physics Range Of Motion, Articular Research Article Torso Viscosity Weight-Bearing Young Adult
Source:
PLoS One. 2012; 7(11).
Pubmed ID:
23144913
Pubmed Central ID:
PMC3489838
Document Type:
Journal Article
Funding:
R01-OH008504/OH/NIOSH CDC HHS/United States
Collection(s):
CDC Public Access
Main Document Checksum:
[+]
urn:sha256:d24dd0de1126063c52eb268a99ee648777a762cd96f1d7719c0134aebf43c8f0
Download URL:
https://stacks.cdc.gov/view/cdc/22690/cdc_22690_DS1.pdf
File Type:

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