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Author Notes:

Coordinating Author: Lena H. Ting, lting@emory.edu, Phone: 404.894.5216, Fax: 404.385.5044, Address: 313 Ferst Drive, Atlanta, Georgia 30332-0535.

The authors declare that they have no conflicts of interest.

Air Products and NIH had no role in the design, performance, or interpretation of the study.

Subjects:

Research Funding:

Air Products Undergraduate Research Award to CSS and NIH grant HD46922 to LHT.

JLA was supported by NIH T32 NS007480.

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Technology
  • Biophysics
  • Engineering, Biomedical
  • Engineering
  • Motor control
  • Musculoskeletal model
  • Muscle coordination
  • Biomechanics
  • Gait
  • LOWER-LIMB MUSCLES
  • STANCE PHASE
  • CROUCH GAIT
  • PATTERNS
  • KNEE
  • OPTIMIZATION
  • SIMULATIONS
  • PREDICTION
  • MOVEMENT
  • COACTIVATION

Feasible muscle activation ranges based on inverse dynamics analyses of human walking

Tools:

Journal Title:

Journal of Biomechanics

Volume:

Volume 48, Number 12

Publisher:

, Pages 2990-2997

Type of Work:

Article | Post-print: After Peer Review

Abstract:

Although it is possible to produce the same movement using an infinite number of different muscle activation patterns owing to musculoskeletal redundancy, the degree to which observed variations in muscle activity can deviate from optimal solutions computed from biomechanical models is not known. Here, we examined the range of biomechanically permitted activation levels in individual muscles during human walking using a detailed musculoskeletal model and experimentally-measured kinetics and kinematics. Feasible muscle activation ranges define the minimum and maximum possible level of each muscle's activation that satisfy inverse dynamics joint torques assuming that all other muscles can vary their activation as needed. During walking, 73% of the muscles had feasible muscle activation ranges that were greater than 95% of the total muscle activation range over more than 95% of the gait cycle, indicating that, individually, most muscles could be fully active or fully inactive while still satisfying inverse dynamics joint torques. Moreover, the shapes of the feasible muscle activation ranges did not resemble previously-reported muscle activation patterns nor optimal solutions, i.e. static optimization and computed muscle control, that are based on the same biomechanical constraints. Our results demonstrate that joint torque requirements from standard inverse dynamics calculations are insufficient to define the activation of individual muscles during walking in healthy individuals. Identifying feasible muscle activation ranges may be an effective way to evaluate the impact of additional biomechanical and/or neural constraints on possible versus actual muscle activity in both normal and impaired movements.

Copyright information:

© 2015 Elsevier Ltd.

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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