Jennifer Wegrzyk1, Alexandre Fouré1, Christophe Vilmen1, Badih Ghattas2, Nicola A Maffiuletti3, Jean-Pierre Mattei4, Nicolas Place5, David Bendahan1, Julien Gondin6. 1. Aix Marseille Université, CNRS, CRMBM UMR 7339, 13385 Marseille, France. 2. Aix Marseille Université, CNRS, Institut de Mathématiques, UMR 7373, 13288 Marseille, France. 3. Neuromuscular Research Laboratory, Schulthess Clinic, Zurich, Switzerland. 4. Aix Marseille Université, CNRS, CRMBM UMR 7339, 13385 Marseille, France; APHM, Hôpital Sainte Marguerite, Service de Rhumatologie, 13009 Marseille, France. 5. Institute of Sport Sciences and Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland. 6. Aix Marseille Université, CNRS, CRMBM UMR 7339, 13385 Marseille, France. Electronic address: julien.gondin@univ-amu.fr.
Abstract
OBJECTIVE: In contrast to conventional (CONV) neuromuscular electrical stimulation (NMES), the use of "wide-pulse, high-frequencies" (WPHF) can generate higher forces than expected by the direct activation of motor axons alone. We aimed at investigating the occurrence, magnitude, variability and underlying neuromuscular mechanisms of these "Extra Forces" (EF). METHODS:Electrically-evoked isometric plantar flexion force was recorded in 42 healthy subjects. Additionally, twitch potentiation, H-reflex and M-wave responses were assessed in 13 participants. CONV (25Hz, 0.05ms) and WPHF (100Hz, 1ms) NMES consisted of five stimulation trains (20s on-90s off). RESULTS: K-means clustering analysis disclosed a responder rate of almost 60%. Within this group of responders, force significantly increased from 4% to 16% of the maximal voluntary contraction force and H-reflexes were depressed after WPHF NMES. In contrast, non-responders showed neither EF nor H-reflex depression. Twitch potentiation and resting EMG data were similar between groups. Interestingly, a large inter- and intrasubject variability of EF was observed. CONCLUSION: The responder percentage was overestimated in previous studies. SIGNIFICANCE: This study proposes a novel methodological framework for unraveling the neurophysiological mechanisms involved in EF and provides further evidence for a central contribution to EF in responders.
RCT Entities:
OBJECTIVE: In contrast to conventional (CONV) neuromuscular electrical stimulation (NMES), the use of "wide-pulse, high-frequencies" (WPHF) can generate higher forces than expected by the direct activation of motor axons alone. We aimed at investigating the occurrence, magnitude, variability and underlying neuromuscular mechanisms of these "Extra Forces" (EF). METHODS: Electrically-evoked isometric plantar flexion force was recorded in 42 healthy subjects. Additionally, twitch potentiation, H-reflex and M-wave responses were assessed in 13 participants. CONV (25Hz, 0.05ms) and WPHF (100Hz, 1ms) NMES consisted of five stimulation trains (20s on-90s off). RESULTS: K-means clustering analysis disclosed a responder rate of almost 60%. Within this group of responders, force significantly increased from 4% to 16% of the maximal voluntary contraction force and H-reflexes were depressed after WPHF NMES. In contrast, non-responders showed neither EF nor H-reflex depression. Twitch potentiation and resting EMG data were similar between groups. Interestingly, a large inter- and intrasubject variability of EF was observed. CONCLUSION: The responder percentage was overestimated in previous studies. SIGNIFICANCE: This study proposes a novel methodological framework for unraveling the neurophysiological mechanisms involved in EF and provides further evidence for a central contribution to EF in responders.
Authors: Vanesa Bochkezanian; Robert U Newton; Gabriel S Trajano; Amilton Vieira; Timothy S Pulverenti; Anthony J Blazevich Journal: BMC Neurol Date: 2018-02-13 Impact factor: 2.474
Authors: Chris Donnelly; Jonathan Stegmüller; Anthony J Blazevich; Fabienne Crettaz von Roten; Bengt Kayser; Daria Neyroud; Nicolas Place Journal: Sci Rep Date: 2021-03-18 Impact factor: 4.379
Authors: Jennifer Wegrzyk; Alexandre Fouré; Yann Le Fur; Nicola A Maffiuletti; Christophe Vilmen; Maxime Guye; Jean-Pierre Mattei; Nicolas Place; David Bendahan; Julien Gondin Journal: PLoS One Date: 2015-11-30 Impact factor: 3.240