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Author Notes:

Correspondence to: Lena H. Ting.

We thank J. Lucas McKay and Nathan E. Bunderson for their helpful comments on the methods and the manuscript.

Subjects:

Research Funding:

Supported by NIH grant HD46922.

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Technology
  • Biophysics
  • Engineering, Biomedical
  • Engineering
  • biomechanics
  • musculoskeletal model
  • muscle
  • posture
  • cat hindlimb
  • ankle
  • balance
  • induced accelerations
  • DYNAMICAL SIMULATIONS
  • HETEROGENIC REFLEXES
  • QUADRUPEDAL STANCE
  • LOCOMOTION
  • COORDINATION
  • BEHAVIOR
  • SPEED
  • GAIT
  • CONSTRUCTION
  • STRATEGIES

Inter-joint coupling effects on muscle contributions to endpoint force and acceleration in a musculoskeletal model of the cat hindlimb

Tools:

Journal Title:

Journal of Biomechanical Engineering

Volume:

Volume 40, Number 16

Publisher:

, Pages 3570-3579

Type of Work:

Article | Post-print: After Peer Review

Abstract:

The biomechanical principles underlying the organization of muscle activation patterns during standing balance are poorly understood. The goal of this study was to understand the influence of biomechanical inter-joint coupling on endpoint forces and accelerations induced by the activation of individual muscles during postural tasks. We calculated induced endpoint forces and accelerations of 31 muscles in a 7 degree-of-freedom, three-dimensional model of the cat hindlimb. To test the effects of inter-joint coupling, we systematically immobilized the joints (excluded kinematic degrees of freedom) and evaluated how the endpoint force and acceleration directions changed for each muscle in 7 different conditions. We hypothesized that altered inter-joint coupling due to joint immobilization of remote joints would substantially change the induced directions of endpoint force and acceleration of individual muscles. Our results show that for most muscles crossing the knee or the hip, joint immobilization altered the endpoint force or acceleration direction by more than 90° in the dorsal and sagittal planes. Induced endpoint forces were typically consistent with behaviorally observed forces only when the ankle was immobilized. We then activated a proximal muscle simultaneous with an ankle torque of varying magnitude, which demonstrated that the resulting endpoint force or acceleration direction is modulated by the magnitude of the ankle torque. We argue that this simple manipulation can lend insight into the functional effects of co-activating muscles. We conclude that inter-joint coupling may be an essential biomechanical principle underlying the coordination of proximal and distal muscles to produce functional endpoint actions during motor tasks.

Copyright information:

© 2007 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/).

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