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Strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics

In terrestrial locomotion, muscles undergo damped oscillations in response to limb impacts with the ground. Muscles are also actuators that generate mechanical power to allow locomotion. The corresponding elementary contractile process is the work stroke of an actin-myosin cross-bridge, which may be...

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Autores principales: Christensen, Kasper B., Günther, Michael, Schmitt, Syn, Siebert, Tobias
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5643554/
https://www.ncbi.nlm.nih.gov/pubmed/29038526
http://dx.doi.org/10.1038/s41598-017-13630-7
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author Christensen, Kasper B.
Günther, Michael
Schmitt, Syn
Siebert, Tobias
author_facet Christensen, Kasper B.
Günther, Michael
Schmitt, Syn
Siebert, Tobias
author_sort Christensen, Kasper B.
collection PubMed
description In terrestrial locomotion, muscles undergo damped oscillations in response to limb impacts with the ground. Muscles are also actuators that generate mechanical power to allow locomotion. The corresponding elementary contractile process is the work stroke of an actin-myosin cross-bridge, which may be forcibly detached by superposed oscillations. By experimentally emulating rat leg impacts, we found that full activity and non-fatigue must meet to possibly prevent forcible cross-bridge detachment. Because submaximal muscle force represents the ordinary locomotor condition, our results show that forcible, eccentric cross-bridge detachment is a common, physiological process even during isometric muscle contractions. We also calculated the stiffnesses of the whole muscle-tendon complex and the fibre material separately, as well as Young’s modulus of the latter: 1.8 MPa and 0.75 MPa for fresh, fully active and passive fibres, respectively. Our inferred Young’s modulus of the tendon-aponeurosis complex suggests that stiffness in series to the fibre material is determined by the elastic properties of the aponeurosis region, rather than the tendon material. Knowing these stiffnesses and the muscle mass, the complex’ eigenfrequency for responses to impacts can be quantified, as well as the size-dependency of this time scale of muscular wobbling mass dynamics.
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spelling pubmed-56435542017-10-19 Strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics Christensen, Kasper B. Günther, Michael Schmitt, Syn Siebert, Tobias Sci Rep Article In terrestrial locomotion, muscles undergo damped oscillations in response to limb impacts with the ground. Muscles are also actuators that generate mechanical power to allow locomotion. The corresponding elementary contractile process is the work stroke of an actin-myosin cross-bridge, which may be forcibly detached by superposed oscillations. By experimentally emulating rat leg impacts, we found that full activity and non-fatigue must meet to possibly prevent forcible cross-bridge detachment. Because submaximal muscle force represents the ordinary locomotor condition, our results show that forcible, eccentric cross-bridge detachment is a common, physiological process even during isometric muscle contractions. We also calculated the stiffnesses of the whole muscle-tendon complex and the fibre material separately, as well as Young’s modulus of the latter: 1.8 MPa and 0.75 MPa for fresh, fully active and passive fibres, respectively. Our inferred Young’s modulus of the tendon-aponeurosis complex suggests that stiffness in series to the fibre material is determined by the elastic properties of the aponeurosis region, rather than the tendon material. Knowing these stiffnesses and the muscle mass, the complex’ eigenfrequency for responses to impacts can be quantified, as well as the size-dependency of this time scale of muscular wobbling mass dynamics. Nature Publishing Group UK 2017-10-16 /pmc/articles/PMC5643554/ /pubmed/29038526 http://dx.doi.org/10.1038/s41598-017-13630-7 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Christensen, Kasper B.
Günther, Michael
Schmitt, Syn
Siebert, Tobias
Strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics
title Strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics
title_full Strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics
title_fullStr Strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics
title_full_unstemmed Strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics
title_short Strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics
title_sort strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5643554/
https://www.ncbi.nlm.nih.gov/pubmed/29038526
http://dx.doi.org/10.1038/s41598-017-13630-7
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