Mathematical model that predicts isometric muscle forces for individuals with spinal cord injuries

Jun Ding, Samuel C K Lee, Therese E. Johnston, Anthony S. Wexler, Wayne B. Scott, Stuart A. Binder-Macleod

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


The ideal functional electrical stimulation (FES) system requires a mathematical model to provide feedforward control of the stimulation parameters such that they are optimal for different individuals across a range of physiological conditions, muscles, and tasks. Recently we tested and validated such a model using able-bodied subjects. The purpose of this study was to determine whether this model applied to persons with spinal cord injuries (SCI). To this end, the isometric force responses of the paralyzed quadriceps femoris muscles of 14 adolescents and young adults were tested. For each subject, the force responses to two six-pulse stimulation trains were used to identify the parameter values of the model and then the model was used to predict the force responses to three train patterns across a range of frequencies in both a nonfatigued and fatigued condition. The intraclass correlation coefficients (ICCs) between the experimental and predicted force-time integrals and peak forces were above 0.90 for 12 of the 13 stimulation trains tested in the nonfatigued condition and all 13 trains tested in the fatigued condition. The success of our model with SCI subjects leads us to believe that our model may be useful for designing optimal stimulation parameters for standing and ambulation in patients who use FES.

Original languageEnglish (US)
Pages (from-to)702-712
Number of pages11
JournalMuscle and Nerve
Issue number6
StatePublished - Jun 2005


  • Functional electrical stimulation
  • Human quadriceps femoris
  • Muscle fatigue

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


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