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Title:Motor unit discharge rate modulation during isometric contractions to failure is intensity- and modality-dependent
Authors:ID Valenčič, Tamara (Author)
ID Ansdell, Paul (Author)
ID Brownstein, Callum G. (Author)
ID Spillane, Padraig M. (Author)
ID Holobar, Aleš (Author)
ID Škarabot, Jakob (Author)
Files:URL https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP286143
 
.pdf The_Journal_of_Physiology_-_2024_-_Valencic_-_Motor_unit_discharge_rate_modulation_during_isometric_contractions_to_failure.pdf (3,77 MB)
MD5: 89E25EBBC3D02CD031078552DDA3C59D
 
Language:English
Work type:Article
Typology:1.01 - Original Scientific Article
Organization:FERI - Faculty of Electrical Engineering and Computer Science
Abstract:The physiological mechanisms determining the progressive decline in the maximal muscle torque production capacity during isometric contractions to task failure are known to depend on task demands. Task-specificity of the associated adjustments in motor unit discharge rate (MUDR), however, remains unclear. This study examined MUDR adjustments during different submaximal isometric knee extension tasks to failure. Participants performed a sustained and an intermittent task at 20% and 50% of maximal voluntary torque (MVT), respectively (Experiment 1). High-density surface EMG signals were recorded from vastus lateralis (VL) and medialis (VM) and decomposed into individual MU discharge timings, with the identified MUs tracked from recruitment to task failure. MUDR was quantified and normalised to intervals of 10% of contraction time (CT). MUDR of both muscles exhibited distinct modulation patterns in each task. During the 20% MVT sustained task, MUDR decreased until ∼50% CT, after which it gradually returned to baseline. Conversely, during the 50% MVT intermittent task, MUDR remained stable until ∼40–50% CT, after which it started to continually increase until task failure. To explore the effect of contraction intensity on the observed patterns, VL and VM MUDR was quantified during sustained contractions at 30% and 50% MVT (Experiment 2). During the 30% MVT sustained task, MUDR remained stable until ∼80–90% CT in both muscles, after which it continually increased until task failure. During the 50% MVT sustained task the increase in MUDR occurred earlier, after ∼70–80% CT. Our results suggest that adjustments in MUDR during submaximal isometric contractions to failure are contraction modality- and intensity-dependent.
Keywords:muscle contractions, high-density EMG signals, electromyiograms
Publication date:15.04.2024
Publisher:Wiley
Year of publishing:2024
Number of pages:Str. 2287-2314
Numbering:Vol. 602, iss. 10
PID:20.500.12556/DKUM-90160 New window
UDC:61:004.8
ISSN on article:1469-7793
COBISS.SI-ID:192788739 New window
DOI:10.1113/JP286143 New window
Publication date in DKUM:23.08.2024
Views:117
Downloads:10
Metadata:XML DC-XML DC-RDF
Categories:Misc.
:
VALENČIČ, Tamara, ANSDELL, Paul, BROWNSTEIN, Callum G., SPILLANE, Padraig M., HOLOBAR, Aleš and ŠKARABOT, Jakob, 2024, Motor unit discharge rate modulation during isometric contractions to failure is intensity- and modality-dependent. The journal of physiology [online]. 2024. Vol. 602, no. 10, p. 2287–2314. [Accessed 13 April 2025]. DOI 10.1113/JP286143. Retrieved from: https://dk.um.si/IzpisGradiva.php?lang=eng&id=90160
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Record is a part of a journal

Title:The journal of physiology
Shortened title:J. physiol.
Publisher:Cambridge University Press
ISSN:1469-7793
COBISS.SI-ID:515030553 New window

Document is financed by a project

Funder:ARIS - Slovenian Research and Innovation Agency
Project number:J2-1731
Name:Dekompozicija sestavljenih mišičnih potencialov
Funder:ARIS - Slovenian Research and Innovation Agency
Project number:P2-0041
Name:Računalniški sistemi, metodologije in inteligentne storitve

Secondary language

Language:Slovenian
Keywords:elektromiogrami, signali EMG, kontrakcija mišic


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