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

Cole S. Simpson, M. Hongchul Sohn, Jessica L. Allen, Lena H. Ting*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


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.

Original languageEnglish (US)
Article number7281
Pages (from-to)2990-2997
Number of pages8
JournalJournal of Biomechanics
Issue number12
StatePublished - Sep 18 2015
Externally publishedYes


  • Biomechanics
  • Gait
  • Motor control
  • Muscle coordination
  • Musculoskeletal model

ASJC Scopus subject areas

  • Biophysics
  • Rehabilitation
  • Biomedical Engineering
  • Orthopedics and Sports Medicine


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