M-wave changes caused by brief voluntary and stimulated isometric contractions

Autor: Javier Rodriguez-Falces, Armando Malanda, Javier Navallas, Nicolas Place
Rok vydání: 2023
Předmět:
Zdroj: European Journal of Applied Physiology.
ISSN: 1439-6327
1439-6319
DOI: 10.1007/s00421-023-05228-x
Popis: Introduction Under isometric conditions, the increase in muscle force is accompanied by a reduction in the fibers’ length. The effects of muscle shortening on the compound muscle action potential (M wave) have so far been investigated only by computer simulation. This study was undertaken to assess experimentally the M-wave changes caused by brief voluntary and stimulated isometric contractions. Methods Two different methods of inducing muscle shortening under isometric condition were adopted: (1) applying a brief (1 s) tetanic contraction and (2) performing brief voluntary contractions of different intensities. In both methods, supramaximal stimulation was applied to the brachial plexus and femoral nerves to evoke M waves. In the first method, electrical stimulation (20 Hz) was delivered with the muscle at rest, whereas in the second, stimulation was applied while participants performed 5-s stepwise isometric contractions at 10, 20, 30, 40, 50, 60, 70, and 100% MVC. The amplitude and duration of the first and second M-wave phases were computed. Results The main findings were: (1) on application of tetanic stimulation, the amplitude of the M-wave first phase decreased (~ 10%, P P P P P P Conclusions The present results will help to identify the adjustments in the M-wave profile caused by muscle shortening and also contribute to differentiate these adjustments from those caused by muscle fatigue and/or changes in Na+–K+ pump activity.
Databáze: OpenAIRE
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