About this item:

12 Views | 0 Downloads

Author Notes:

Lena H. Ting:The Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, 313 Ferst Drive, Atlanta, GA 30322-0535, U.S.A; School of Applied Physiology, Georgia Institute of Technology, Atlanta, GA, USA, lena.ting@bme.gatech.edu

Authors have no conflict of interest to report.

Subjects:

Research Funding:

Supported by NIH grant HD46922.

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Technology
  • Biophysics
  • Engineering, Biomedical
  • Engineering
  • neuromuscular
  • biomechanical model
  • posture
  • balance
  • cat hindlimb
  • motor control
  • modes of movement
  • moment arm
  • neuromechanics
  • force sharing
  • muscle activation pattern
  • feedforward neural control
  • ANKLE MUSCLE-STIFFNESS
  • CHRONIC SPINAL CAT
  • HINDLIMB
  • BALANCE
  • MODEL
  • SUPPORT
  • LENGTH
  • STANCE
  • STRATEGIES
  • RESPONSES

Reduction of neuromuscular redundancy for postural force generation using an intrinsic stability criterion

Tools:

Journal Title:

Journal of Biomechanics

Volume:

Volume 41, Number 7

Publisher:

, Pages 1537-1544

Type of Work:

Article | Post-print: After Peer Review

Abstract:

Postural control requires the coordination of multiple muscles to achieve both endpoint force production and postural stability. Multiple muscle activation patterns can produce the required force for standing, but the mechanical stability associated with any given pattern may vary, and has implications for the degree of delayed neural feedback necessary for postural stability. We hypothesized that muscular redundancy is reduced when muscle activation patterns are chosen with respect to intrinsic musculoskeletal stability as well as endpoint force production. We used a three-dimensional musculoskeletal model of the cat hindlimb with 31 muscles to determine the possible contributions of intrinsic muscle properties to limb stability during isometric force generation. Using dynamic stability analysis we demonstrate that within the large set of activation patterns that satisfy the force requirement for posture, only a reduced subset produce a mechanically stable limb configuration. Greater stability in the frontal-plane suggests that neural control mechanisms are more highly active for sagittal-plane and for ankle joint control. Even when the limb was unstable, the time-constants of instability were sufficiently great to allow long-latency neural feedback mechanisms to intervene, which may be preferential for movements requiring maneuverability versus stability. Local joint stiffness of muscles was determined by the stabilizing or destabilizing effects of moment-arm versus joint angle relationships. By preferentially activating muscles with high local stiffness, muscle activation patterns with feedforward stabilizing properties could be selected. Such a strategy may increase intrinsic postural stability without co-contraction, and may be useful criteria in the force-sharing problem.

Copyright information:

© 2008 Elsevier Ltd. All rights reserved.

This is an Open Access work distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Creative Commons License

Export to EndNote