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Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques

Behavioral evidence has suggested that a small number of muscle synergies may be responsible for activating a variety of muscles. Nevertheless, such dimensionality reduction may also be explained using the perspective of alternative hypotheses, such as predictions based on linear combinations of joi...

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Autores principales: Suzuki, Takahito, Kinugasa, Ryuta, Fukashiro, Senshi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673179/
https://www.ncbi.nlm.nih.gov/pubmed/29107958
http://dx.doi.org/10.1371/journal.pone.0187587
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author Suzuki, Takahito
Kinugasa, Ryuta
Fukashiro, Senshi
author_facet Suzuki, Takahito
Kinugasa, Ryuta
Fukashiro, Senshi
author_sort Suzuki, Takahito
collection PubMed
description Behavioral evidence has suggested that a small number of muscle synergies may be responsible for activating a variety of muscles. Nevertheless, such dimensionality reduction may also be explained using the perspective of alternative hypotheses, such as predictions based on linear combinations of joint torques multiplied by corresponding coefficients. To compare the explanatory capacity of these hypotheses for describing muscle activation, we enrolled 12 male volunteers who performed isometric plantar flexor contractions at 10–100% of maximum effort. During each plantar flexor contraction, the knee extensor muscles were isometrically contracted at 0%, 50%, or 100% of maximum effort. Electromyographic activity was recorded from the vastus lateralis, medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus muscles and quantified using the average rectified value (ARV). At lower plantar flexion torque, regression analysis identified a clear linear relationship between the MG and soleus ARVs and between the MG and LG ARVs, suggesting the presence of muscle synergy (r(2) > 0.65). The contraction of the knee extensor muscles induced a significant change in the slope of this relationship for both pairs of muscles (MG × soleus, P = 0.002; MG × LG, P = 0.006). Similarly, the slope of the linear relationship between the plantar flexion torque and the ARV of the MG or soleus changed significantly with knee extensor contraction (P = 0.031 and P = 0.041, respectively). These results suggest that muscle synergies characterized by non-mechanical constraints are selectively recruited according to whether contraction of the knee extensor muscles is performed simultaneously, which is relatively consistent with the muscle synergy hypothesis.
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spelling pubmed-56731792017-11-18 Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques Suzuki, Takahito Kinugasa, Ryuta Fukashiro, Senshi PLoS One Research Article Behavioral evidence has suggested that a small number of muscle synergies may be responsible for activating a variety of muscles. Nevertheless, such dimensionality reduction may also be explained using the perspective of alternative hypotheses, such as predictions based on linear combinations of joint torques multiplied by corresponding coefficients. To compare the explanatory capacity of these hypotheses for describing muscle activation, we enrolled 12 male volunteers who performed isometric plantar flexor contractions at 10–100% of maximum effort. During each plantar flexor contraction, the knee extensor muscles were isometrically contracted at 0%, 50%, or 100% of maximum effort. Electromyographic activity was recorded from the vastus lateralis, medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus muscles and quantified using the average rectified value (ARV). At lower plantar flexion torque, regression analysis identified a clear linear relationship between the MG and soleus ARVs and between the MG and LG ARVs, suggesting the presence of muscle synergy (r(2) > 0.65). The contraction of the knee extensor muscles induced a significant change in the slope of this relationship for both pairs of muscles (MG × soleus, P = 0.002; MG × LG, P = 0.006). Similarly, the slope of the linear relationship between the plantar flexion torque and the ARV of the MG or soleus changed significantly with knee extensor contraction (P = 0.031 and P = 0.041, respectively). These results suggest that muscle synergies characterized by non-mechanical constraints are selectively recruited according to whether contraction of the knee extensor muscles is performed simultaneously, which is relatively consistent with the muscle synergy hypothesis. Public Library of Science 2017-11-06 /pmc/articles/PMC5673179/ /pubmed/29107958 http://dx.doi.org/10.1371/journal.pone.0187587 Text en © 2017 Suzuki et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Suzuki, Takahito
Kinugasa, Ryuta
Fukashiro, Senshi
Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques
title Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques
title_full Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques
title_fullStr Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques
title_full_unstemmed Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques
title_short Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques
title_sort activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673179/
https://www.ncbi.nlm.nih.gov/pubmed/29107958
http://dx.doi.org/10.1371/journal.pone.0187587
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