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Reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability

After active lengthening contractions, a given amount of force can be maintained with less muscle activation compared to pure isometric contractions at the same muscle length and intensity. This increase in neuromuscular efficiency is associated with mechanisms of stretch-induced residual force enha...

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Autores principales: Seiberl, W., Hahn, D., Paternoster, F. K.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5155269/
https://www.ncbi.nlm.nih.gov/pubmed/27966620
http://dx.doi.org/10.1038/srep39052
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author Seiberl, W.
Hahn, D.
Paternoster, F. K.
author_facet Seiberl, W.
Hahn, D.
Paternoster, F. K.
author_sort Seiberl, W.
collection PubMed
description After active lengthening contractions, a given amount of force can be maintained with less muscle activation compared to pure isometric contractions at the same muscle length and intensity. This increase in neuromuscular efficiency is associated with mechanisms of stretch-induced residual force enhancement. We hypothesized that stretch-related increase in neuromuscular efficiency reduces fatigability of a muscle during submaximal contractions. 13 subjects performed 60 s isometric knee extensions at 60% of maximum voluntary contraction (MVC) with and without prior stretch (60°/s, 20°). Each 60 s trial was preceded and followed by neuromuscular tests consisting of MVCs, voluntary activation (VA) and resting twitches (RT), and there was 4 h rest between sets. We found a significant (p = 0.036) 10% reduction of quadriceps net-EMG after lengthening compared to pure isometric trials. However, increase in neuromuscular efficiency did not influence the development of fatigue. Albeit we found severe reduction of MVC (30%), RT (30%) and VA (5%) after fatiguing trials, there were no differences between conditions with and without lengthening. As the number of subjects showing no activation reduction increased with increasing contraction time, intensity may have been too strenuous in both types of contractions, such that a distinction between different states of fatigue was not possible anymore.
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spelling pubmed-51552692016-12-28 Reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability Seiberl, W. Hahn, D. Paternoster, F. K. Sci Rep Article After active lengthening contractions, a given amount of force can be maintained with less muscle activation compared to pure isometric contractions at the same muscle length and intensity. This increase in neuromuscular efficiency is associated with mechanisms of stretch-induced residual force enhancement. We hypothesized that stretch-related increase in neuromuscular efficiency reduces fatigability of a muscle during submaximal contractions. 13 subjects performed 60 s isometric knee extensions at 60% of maximum voluntary contraction (MVC) with and without prior stretch (60°/s, 20°). Each 60 s trial was preceded and followed by neuromuscular tests consisting of MVCs, voluntary activation (VA) and resting twitches (RT), and there was 4 h rest between sets. We found a significant (p = 0.036) 10% reduction of quadriceps net-EMG after lengthening compared to pure isometric trials. However, increase in neuromuscular efficiency did not influence the development of fatigue. Albeit we found severe reduction of MVC (30%), RT (30%) and VA (5%) after fatiguing trials, there were no differences between conditions with and without lengthening. As the number of subjects showing no activation reduction increased with increasing contraction time, intensity may have been too strenuous in both types of contractions, such that a distinction between different states of fatigue was not possible anymore. Nature Publishing Group 2016-12-14 /pmc/articles/PMC5155269/ /pubmed/27966620 http://dx.doi.org/10.1038/srep39052 Text en Copyright © 2016, The Author(s) http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Seiberl, W.
Hahn, D.
Paternoster, F. K.
Reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability
title Reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability
title_full Reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability
title_fullStr Reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability
title_full_unstemmed Reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability
title_short Reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability
title_sort reduced activation in isometric muscle action after lengthening contractions is not accompanied by reduced performance fatigability
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5155269/
https://www.ncbi.nlm.nih.gov/pubmed/27966620
http://dx.doi.org/10.1038/srep39052
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