Relationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors

Abstract Because it is difficult to measure tendon length changes directly in humans, tendon length changes during dynamic movement have been evaluated indirectly from changes in muscle fascicle length and joint angle. The purpose of this study was to examine the validity of the indirect method. Twi...

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Autores principales:	Atsuki Fukutani, Jun Misaki, Tadao Isaka
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/8b54195b60ce4ce587db4cade9d458e3
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spelling	oai:doaj.org-article:8b54195b60ce4ce587db4cade9d458e32021-12-02T15:05:48ZRelationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors10.1038/s41598-017-00485-12045-2322https://doaj.org/article/8b54195b60ce4ce587db4cade9d458e32017-03-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-00485-1https://doaj.org/toc/2045-2322Abstract Because it is difficult to measure tendon length changes directly in humans, tendon length changes during dynamic movement have been evaluated indirectly from changes in muscle fascicle length and joint angle. The purpose of this study was to examine the validity of the indirect method. Twitch contractions of the ankle plantar flexors were evoked isometrically in eight subjects. Twitch contractions evoked by singlet, doublet, and triplet stimulations were conducted at dorsiflexion 20° (DF20), plantar flexion 0° (PF0), and plantar flexion 20° (PF20). Muscle fascicle length and pennation angle were recorded by ultrasonography. The magnitude of muscle fascicle shortening was significantly smaller in DF20 than in PF0 and PF20, although the magnitude of joint torque was significantly larger in DF20 than in PF0 and PF20. Theoretically, the magnitude of tendon elongation is expected to be larger in larger joint torque conditions. However, we found that the magnitude of tendon elongation evaluated from muscle fascicle shortening was larger in a lower joint torque condition (PF20). These results suggest that the magnitude of muscle fascicle shortening does not necessarily represent tendon elongation. The larger muscle fascicle shortening in PF20 may be partly caused by eliminating slack of the muscle-tendon complex.Atsuki FukutaniJun MisakiTadao IsakaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-6 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Atsuki Fukutani Jun Misaki Tadao Isaka Relationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors
description	Abstract Because it is difficult to measure tendon length changes directly in humans, tendon length changes during dynamic movement have been evaluated indirectly from changes in muscle fascicle length and joint angle. The purpose of this study was to examine the validity of the indirect method. Twitch contractions of the ankle plantar flexors were evoked isometrically in eight subjects. Twitch contractions evoked by singlet, doublet, and triplet stimulations were conducted at dorsiflexion 20° (DF20), plantar flexion 0° (PF0), and plantar flexion 20° (PF20). Muscle fascicle length and pennation angle were recorded by ultrasonography. The magnitude of muscle fascicle shortening was significantly smaller in DF20 than in PF0 and PF20, although the magnitude of joint torque was significantly larger in DF20 than in PF0 and PF20. Theoretically, the magnitude of tendon elongation is expected to be larger in larger joint torque conditions. However, we found that the magnitude of tendon elongation evaluated from muscle fascicle shortening was larger in a lower joint torque condition (PF20). These results suggest that the magnitude of muscle fascicle shortening does not necessarily represent tendon elongation. The larger muscle fascicle shortening in PF20 may be partly caused by eliminating slack of the muscle-tendon complex.
format	article
author	Atsuki Fukutani Jun Misaki Tadao Isaka
author_facet	Atsuki Fukutani Jun Misaki Tadao Isaka
author_sort	Atsuki Fukutani
title	Relationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors
title_short	Relationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors
title_full	Relationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors
title_fullStr	Relationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors
title_full_unstemmed	Relationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors
title_sort	relationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/8b54195b60ce4ce587db4cade9d458e3
work_keys_str_mv	AT atsukifukutani relationshipbetweenjointtorqueandmusclefascicleshorteningatvariousjointanglesandintensitiesintheplantarflexors AT junmisaki relationshipbetweenjointtorqueandmusclefascicleshorteningatvariousjointanglesandintensitiesintheplantarflexors AT tadaoisaka relationshipbetweenjointtorqueandmusclefascicleshorteningatvariousjointanglesandintensitiesintheplantarflexors
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Relationship between joint torque and muscle fascicle shortening at various joint angles and intensities in the plantar flexors

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