Document Type
Journal Article
Publication Title
European Journal of Applied Physiology
Publisher
Springer
School
Centre for Human Performance / School of Medical and Health Sciences
RAS ID
70466
Funders
Swiss National Science Foundation / University of Lausanne
Grant Number
32003B_204364/1
Abstract
Purpose: To assess the effect of a remote handgrip contraction during wide-pulse high-frequency (WPHF) neuromuscular electrical stimulation (NMES) on the magnitude of extra torque, progressive increase in torque during stimulation, and estimates of the persistent inward current (PIC) contribution to motoneuron firing in the plantar flexors. Methods: Ten participants performed triangular shaped contractions to 20% of maximal plantar flexion torque before and after WPHF NMES with and without a handgrip contraction, and control conditions. Extra torque, the relative difference between the initial and final torque during stimulation, and sustained electromyographic (EMG) activity were assessed. High-density EMG was recorded during triangular shaped contractions to calculate ∆F, an estimate of PIC contribution to motoneuron firing, and its variation before vs after the intervention referred to as ∆F change score. Results: While extra torque was not significantly increased with remote contraction (WPHF + remote) vs WPHF (+ 37 ± 63%, p = 0.112), sustained EMG activity was higher in this condition than WPHF (+ 3.9 ± 4.3% MVC EMG, p = 0.017). Moreover, ∆F was greater (+ 0.35 ± 0.30 Hz) with WPHF + remote than control (+ 0.03 ± 0.1 Hz, p = 0.028). A positive correlation was found between ∆F change score and extra torque in the WPHF + remote (r = 0.862, p = 0.006). Discussion: The findings suggest that the addition of remote muscle contraction to WPHF NMES enhances the central contribution to torque production, which may be related to an increased PIC contribution to motoneuron firing. Gaining a better understanding of these mechanisms should enable NMES intervention optimization in clinical and rehabilitation settings, improving neuromuscular function in clinical populations.
DOI
10.1007/s00421-024-05538-8
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
Popesco, T., Bet da Rosa Orssatto, L., Hug, F., Blazevich, A. J., Trajano, G. S., & Place, N. (2024). Motoneuron persistent inward current contribution to increased torque responses to wide-pulse high-frequency neuromuscular electrical stimulation. European Journal of Applied Physiology. Advance online publication. https://doi.org/10.1007/s00421-024-05538-8