Changes in constraint of proximal segments effects time to task failure and activity of proximal muscles in knee position-control tasks

Poortvliet, Peter C., Tucker, Kylie J. and Hodges, Paul W. (2013) Changes in constraint of proximal segments effects time to task failure and activity of proximal muscles in knee position-control tasks. Clinical Neurophysiology, 124 4: 732-739. doi:10.1016/j.clinph.2012.09.025


Author Poortvliet, Peter C.
Tucker, Kylie J.
Hodges, Paul W.
Title Changes in constraint of proximal segments effects time to task failure and activity of proximal muscles in knee position-control tasks
Journal name Clinical Neurophysiology   Check publisher's open access policy
ISSN 1388-2457
1872-8952
Publication date 2013-04
Year available 2012
Sub-type Article (original research)
DOI 10.1016/j.clinph.2012.09.025
Volume 124
Issue 4
Start page 732
End page 739
Total pages 8
Place of publication Shannon, Co. Clare, Ireland
Publisher Elsevier
Collection year 2013
Language eng
Formatted abstract
Objective: Maintenance of a limb position against external load (position-control) fails earlier (time to task failure: TTF) than maintenance of identical force against rigid restraint (force-control). Although possibly explained by physiological differences between contractions, we investigated whether less constraint of movements in other planes and proximal segments (commonly less in position-control tasks) shortens TTF.

Methods: Seventeen adults (32 ± 7 years) contracted knee extensor muscles to task failure in a position-control task, with and without constraint of motion in other planes and proximal segments, and a force-control task with constraints. Electromyography of knee extensors, their antagonist and hip muscles was recorded with force/position.

Results: TTF was shorter for position-control without (161 ± 55 s) than with constraint (184 ± 51 s). Despite identical constraint, TTF was shorter in position- than force-control (216 ± 56 s). Muscle activity and position variability at failure was greater without constraint. Conclusion: Constraint of motion of proximal segments and other planes increases position-control TTF with less muscle activity and variability. As TTF differed between force- and position-control, despite equivalent constraint, other factors contribute to shorter position-control TTF.

Significance: Results clarify that differences in the TTF between position- and force-control tasks are partly explained by unmatched restriction of motion in other planes and proximal segments.
Keyword Knee extensor muscles
Motor control
Postural constraint
Proximal muscle activity
Task failure
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online: 25 October 2012.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Health and Rehabilitation Sciences Publications
 
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Created: Mon, 07 Jan 2013, 08:32:15 EST by Ms Kylie Tucker on behalf of School of Health & Rehabilitation Sciences