Predicting non-isometric fatigue induced by electrical stimulation pulse trains as a function of pulse duration

M. Susan Marion, Anthony S. Wexler, Maury L. Hull

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Background: Our previous model of the non-isometric muscle fatigue that occurs during repetitive functional electrical stimulation included models of force, motion, and fatigue and accounted for applied load but not stimulation pulse duration. Our objectives were to: 1) further develop, 2) validate, and 3) present outcome measures for a non-isometric fatigue model that can predict the effect of a range of pulse durations on muscle fatigue. Methods. A computer-controlled stimulator sent electrical pulses to electrodes on the thighs of 25 able-bodied human subjects. Isometric and non-isometric non-fatiguing and fatiguing knee torques and/or angles were measured. Pulse duration (170-600 μs) was the independent variable. Measurements were divided into parameter identification and model validation subsets. Results: The fatigue model was simplified by removing two of three non-isometric parameters. The third remained a function of other model parameters. Between 66% and 77% of the variability in the angle measurements was explained by the new model. Conclusion: Muscle fatigue in response to different stimulation pulse durations can be predicted during non-isometric repetitive contractions.

Original languageEnglish (US)
Article number13
JournalJournal of NeuroEngineering and Rehabilitation
Issue number1
StatePublished - 2013


  • Functional electrical stimulation (FES)
  • Mathematical model
  • Muscle fatigue
  • Non-isometric
  • Pulse duration

ASJC Scopus subject areas

  • Rehabilitation
  • Health Informatics


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