M-wave changes caused by brief voluntary and stimulated isometric contractions
Fecha
2023Versión
Acceso abierto / Sarbide irekia
Tipo
Artículo / Artikulua
Versión
Versión publicada / Argitaratu den bertsioa
Identificador del proyecto
Impacto
|
10.1007/s00421-023-05228-x
Resumen
Introduction Under isometric conditions, the increase in muscle force is accompanied by a reduction in the fbers’ length.
The efects 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. ...
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Introduction Under isometric conditions, the increase in muscle force is accompanied by a reduction in the fbers’ length.
The efects 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 diferent 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 diferent intensities. In both methods,
supramaximal stimulation was applied to the brachial plexus and femoral nerves to evoke M waves. In the frst 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 frst and second M-wave phases were computed.
Results The main fndings were: (1) on application of tetanic stimulation, the amplitude of the M-wave frst phase decreased
(~10%, P<0.05), that of the second phase increased (~50%, P<0.05), and the M-wave duration decreased (~20%, P<0.05)
across the frst fve M waves of the tetanic train and then plateaued for the subsequent responses; (2) when superimposing
a single electrical stimulus on muscle contractions of increasing forces, the amplitude of the M-wave frst phase decreased
(~20%, P<0.05), that of the second phase increased (~30%, P<0.05), and M-wave duration decreased (~30%, P<0.05)
as force was raised from 0 to 60–70% MVC force.
Conclusions The present results will help to identify the adjustments in the M-wave profle caused by muscle shortening
and also contribute to diferentiate these adjustments from those caused by muscle fatigue and/or changes in Na+–K+ pump
activity. [--]
Materias
Fascicle length,
Fiber diameter,
Isometric contraction,
Muscle bulging,
Muscle shortening,
Tetanic stimulation
Editor
Springer
Publicado en
European Journal of Applied Physiology (2023) 123:2087–2098
Departamento
Universidad Pública de Navarra. Departamento de Ingeniería Eléctrica, Electrónica y de Comunicación /
Nafarroako Unibertsitate Publikoa. Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza Saila
Versión del editor
Entidades Financiadoras
Open Access funding provided by Universidad Pública de Navarra. This work has been supported by the Spanish Ministry of Science and Innovation under the project PID2019-109062RB-I00.