Fatigue pp 147-160 | Cite as

Human Motor Units Studied by Spike-Triggered Averaging and Intraneural Motor Axon Stimulation

  • C. K. Thomas
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 384)


When low-threshold motor units are activated at low rates during sustained, weak voluntary contractions, most unit force profiles exhibit fatigue but some show force potentiation. These data, obtained by spike-triggered averaging, are compared to the fatigue resistance of human motor units activated at twitch and tetanic rates by intraneural motor axon stimulation. With the latter technique, representative sampling of the motor units from one muscle group shows that unit force fatigue or potentiation at submaximal frequencies, and contractile rate changes, dictate the shifts in unit force-frequency relationships. More diverse fatigue protocols, and when possible, careful comparisons of data obtained by both these techniques, are needed to further our understanding of the force and frequency changes of single motor units during voluntary and stimulated exercise.


Motor Unit Motor Axon Single Motor Unit Tetanic Force Maximum Voluntary Contraction Force 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • C. K. Thomas
    • 1
  1. 1.The Miami Project to Cure ParalysisUniversity of Miami School of MedicineMiamiUSA

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