title: Effect of neuromuscular electrical stimulation intensity over the tibial nerve trunk on triceps surae muscle fatigue.
abstract: OBJECTIVE
  This study was designed to investigate whether the intensity modulation of a neuromuscular electrical stimulation (NMES) protocol delivered over the nerve trunk of the plantar flexors would lead to differential peripheral and central contributions of muscle fatigue.
  
  
  METHODS
  Three fatiguing isometric protocols of the plantar flexors matched for the same amount of isometric torque-time integral (TTI) were randomly performed including a volitional protocol at 20 % of the maximal voluntary contraction (MVC) and two NMES protocols (one at constant intensity, CST; the other at intensity level progressively adjusted to maintain 20 % of MVC, PROG).
  
  
  RESULTS
  No time x protocol interaction was found for any of the variables. The MVC decreased similarly (≈12 %, p < 0.001) after all protocols, so did the potentiated twitch responses (p = 0.001). Although voluntary activation of the plantar flexors did not change, maximal H-reflex to M-wave ratio of the soleus (SOL) and the gastrocnemius medialis (GM) muscles showed an overall increase (SOL: p = 0.037, GM: p = 0.041), while it remained stable for the gastrocnemius lateralis muscle (p = 0.221). A main time effect was observed only for the SOL maximal V-wave to the superimposed M-wave ratio (p = 0.024) and to the superimposed H-reflex (p = 0.008). While similar central and peripheral adaptations were observed after the three fatiguing protocols, the individual contribution of the three different triceps surae muscles was different.
  
  
  CONCLUSIONS
  Whether the current intensity was increased or not, the adaptations after a NMES protocol yield to similar muscle fatigue adaptations as voluntary contractions likely through similar pathways matching a similar TTI.
authors.affiliation: University of Nice-Sophia Antipolis, Laboratory of Human Motricity Education Sport and Health (EA 6309), Faculty of Sport Sciences, 261, route de Grenoble B.P. 32 59, 06205, Nice Cedex 03, France, doix@unice.fr.
authors.forename: Aude-Clémence M
authors.initials: AC
authors.lastname: Doix
authors.forename: Boris
authors.initials: B
authors.lastname: Matkowski
authors.forename: Alain
authors.initials: A
authors.lastname: Martin
authors.forename: Karin
authors.initials: K
authors.lastname: Roeleveld
authors.forename: Serge S
authors.initials: SS
authors.lastname: Colson
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D006181:H-Reflex; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D011999:Recruitment, Neurophysiological; D013979:Tibial Nerve / Q000502:physiology*