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Modulation of spatial and temporal modules in lower limb muscle activations during walking with simulated reduced gravity

Gravity plays a crucial role in shaping patterned locomotor output to maintain dynamic stability during locomotion. The present study aimed to clarify the gravity-dependent regulation of modules that organize multiple muscle activities during walking in humans. Participants walked on a treadmill at...

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Autores principales: Hagio, Shota, Nakazato, Makoto, Kouzaki, Motoki
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8292403/
https://www.ncbi.nlm.nih.gov/pubmed/34285306
http://dx.doi.org/10.1038/s41598-021-94201-9
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author Hagio, Shota
Nakazato, Makoto
Kouzaki, Motoki
author_facet Hagio, Shota
Nakazato, Makoto
Kouzaki, Motoki
author_sort Hagio, Shota
collection PubMed
description Gravity plays a crucial role in shaping patterned locomotor output to maintain dynamic stability during locomotion. The present study aimed to clarify the gravity-dependent regulation of modules that organize multiple muscle activities during walking in humans. Participants walked on a treadmill at seven speeds (1–6 km h(−1) and a subject- and gravity-specific speed determined by the Froude number (Fr) corresponding to 0.25) while their body weight was partially supported by a lift to simulate walking with five levels of gravity conditions from 0.07 to 1 g. Modules, i.e., muscle-weighting vectors (spatial modules) and phase-dependent activation coefficients (temporal modules), were extracted from 12 lower-limb electromyographic (EMG) activities in each gravity (Fr ~ 0.25) using nonnegative matrix factorization. Additionally, a tensor decomposition model was fit to the EMG data to quantify variables depending on the gravity conditions and walking speed with prescribed spatial and temporal modules. The results demonstrated that muscle activity could be explained by four modules from 1 to 0.16 g and three modules at 0.07 g, and the modules were shared for both spatial and temporal components among the gravity conditions. The task-dependent variables of the modules acting on the supporting phase linearly decreased with decreasing gravity, whereas that of the module contributing to activation prior to foot contact showed nonlinear U-shaped modulation. Moreover, the profiles of the gravity-dependent modulation changed as a function of walking speed. In conclusion, reduced gravity walking was achieved by regulating the contribution of prescribed spatial and temporal coordination in muscle activities.
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spelling pubmed-82924032021-07-22 Modulation of spatial and temporal modules in lower limb muscle activations during walking with simulated reduced gravity Hagio, Shota Nakazato, Makoto Kouzaki, Motoki Sci Rep Article Gravity plays a crucial role in shaping patterned locomotor output to maintain dynamic stability during locomotion. The present study aimed to clarify the gravity-dependent regulation of modules that organize multiple muscle activities during walking in humans. Participants walked on a treadmill at seven speeds (1–6 km h(−1) and a subject- and gravity-specific speed determined by the Froude number (Fr) corresponding to 0.25) while their body weight was partially supported by a lift to simulate walking with five levels of gravity conditions from 0.07 to 1 g. Modules, i.e., muscle-weighting vectors (spatial modules) and phase-dependent activation coefficients (temporal modules), were extracted from 12 lower-limb electromyographic (EMG) activities in each gravity (Fr ~ 0.25) using nonnegative matrix factorization. Additionally, a tensor decomposition model was fit to the EMG data to quantify variables depending on the gravity conditions and walking speed with prescribed spatial and temporal modules. The results demonstrated that muscle activity could be explained by four modules from 1 to 0.16 g and three modules at 0.07 g, and the modules were shared for both spatial and temporal components among the gravity conditions. The task-dependent variables of the modules acting on the supporting phase linearly decreased with decreasing gravity, whereas that of the module contributing to activation prior to foot contact showed nonlinear U-shaped modulation. Moreover, the profiles of the gravity-dependent modulation changed as a function of walking speed. In conclusion, reduced gravity walking was achieved by regulating the contribution of prescribed spatial and temporal coordination in muscle activities. Nature Publishing Group UK 2021-07-20 /pmc/articles/PMC8292403/ /pubmed/34285306 http://dx.doi.org/10.1038/s41598-021-94201-9 Text en © The Author(s) 2021 https://creativecommons.org/licenses/by/4.0/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 licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence 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 licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Article
Hagio, Shota
Nakazato, Makoto
Kouzaki, Motoki
Modulation of spatial and temporal modules in lower limb muscle activations during walking with simulated reduced gravity
title Modulation of spatial and temporal modules in lower limb muscle activations during walking with simulated reduced gravity
title_full Modulation of spatial and temporal modules in lower limb muscle activations during walking with simulated reduced gravity
title_fullStr Modulation of spatial and temporal modules in lower limb muscle activations during walking with simulated reduced gravity
title_full_unstemmed Modulation of spatial and temporal modules in lower limb muscle activations during walking with simulated reduced gravity
title_short Modulation of spatial and temporal modules in lower limb muscle activations during walking with simulated reduced gravity
title_sort modulation of spatial and temporal modules in lower limb muscle activations during walking with simulated reduced gravity
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8292403/
https://www.ncbi.nlm.nih.gov/pubmed/34285306
http://dx.doi.org/10.1038/s41598-021-94201-9
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