The M waves of thebiceps brachiihave a stationary (shoulder-like) component in the first phase: implications and recommendations for M-wave analysis.

Details

Serval ID
serval:BIB_99DEB96EA189
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
The M waves of thebiceps brachiihave a stationary (shoulder-like) component in the first phase: implications and recommendations for M-wave analysis.
Journal
Physiological measurement
Author(s)
Rodriguez-Falces J., Botter A., Vieira T., Place N.
ISSN
1361-6579 (Electronic)
ISSN-L
0967-3334
Publication state
Published
Issued date
09/02/2021
Peer-reviewed
Oui
Volume
42
Number
1
Language
english
Notes
Publication types: Journal Article
Publication Status: aheadofprint
Abstract
We recently documented that compound muscle action potentials (M waves) recorded over the "pennate" vastus lateralis showed a sharp deflection (named as shoulder) in the first phase. Here, we investigated whether such shoulder was also present in M waves evoked in a muscle with different architecture, such as the biceps brachii, with the purpose of elucidating the electrical origin of such feature.
M waves evoked by maximal single shocks to the brachial plexus were recorded in monopolar and bipolar configurations from 72 individuals using large (10-mm diameter) electrodes and from 8 individuals using small (1-mm diameter) electrodes arranged in a linear array. The changes in M-wave features at different locations along the muscle fibers direction were examined.
The shoulder was recognizable in most (87%) monopolar M waves, whereas it was rarely observed (6%) in bipolar derivations. Recordings made along the fibers direction showed that the shoulder was a stationary (non-propagating) feature, with short duration (spiky), which had positive polarity at all locations along the fibers. The latency of the shoulder (9.5 ± 0.5 ms) was significantly shorter than the estimated time taken for the action potentials to reach the biceps tendon (12.8 ms).
The shoulder must be generated by a dipole source, i.e. a source created at a fixed anatomical position, although the exact origin of this dipole is uncertain. Our results suggest that the shoulder may not be due to the end-of-fiber signals formed at the biceps brachii tendon. The shoulder is not related to any specific arrangement of muscle fibers, as it has been observed in both pennate and fusiform muscles. Being a stationary (non-propagating) component, the shoulder is not reliable to study changes in sarcolemmal excitability, and thus should be excluded from the M-wave analysis.
Keywords
Compound muscle action potential, End-of-fiber signals, M wave, Muscle excitability, Muscle-fiber length, Non-propagating components, Volume conduction
Pubmed
Create date
19/09/2020 14:02
Last modification date
13/07/2021 6:37
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