Higher involvement of synergistic muscle than active muscles in ankle plantar flexion

Abstract The aim of this study was to observe the activation characteristics of calf muscles in healthy adults during plantar flexion by a new nonlinear electromyography index. The linear indices of sEMG, including the root mean square (RMS), median frequency (MF), and nonlinear index, degree centra...

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Main Authors: Ying Xu, Jinping Li, Xiaowen Ju, Ying Hou
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-09892-1
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author Ying Xu
Jinping Li
Xiaowen Ju
Ying Hou
author_facet Ying Xu
Jinping Li
Xiaowen Ju
Ying Hou
author_sort Ying Xu
collection DOAJ
description Abstract The aim of this study was to observe the activation characteristics of calf muscles in healthy adults during plantar flexion by a new nonlinear electromyography index. The linear indices of sEMG, including the root mean square (RMS), median frequency (MF), and nonlinear index, degree centrality (DC) of the calf muscles of ten healthy male participants, were tested in the resting state and plantar flexion position to analyse their characteristics. The RMS was not normally distributed, and the MF and DC values were normally distributed. Compared with those in the resting state, the RMS, MF and DC values of all the tested muscles were significantly greater (P < 0.05) during plantar flexion. Among all the muscles, the peroneus longus (PL) changed the most. The RMS increased from 3.14 ± 1.61 µV to 49.31 ± 21.81 µV, the MF increased from 134.07 ± 30.86 Hz to 203.55 ± 28.36 Hz, and the DC changed from 2.24 ± 0.38 to 3.33 ± 0.41. Two linear indices and a nonlinear index of the PL were significantly elevated during prone plantar flexion. We speculate that the nonlinear index, DC can reflect the degree of single muscle synergistic involvement, and may become a new indicator for assessing the state of single muscle controlled by nervous system in a movement involving multiple muscles.
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spelling doaj-art-3879eb88bbf44e369e42642e84f4da9f2025-08-20T03:05:22ZengNature PortfolioScientific Reports2045-23222025-07-011511810.1038/s41598-025-09892-1Higher involvement of synergistic muscle than active muscles in ankle plantar flexionYing Xu0Jinping Li1Xiaowen Ju2Ying Hou3Department of Rehabilitation Medicine, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal HospitalDepartment of Rehabilitation Medicine, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal HospitalDepartment of Rehabilitation Medicine, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal HospitalDepartment of Rehabilitation Medicine, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal HospitalAbstract The aim of this study was to observe the activation characteristics of calf muscles in healthy adults during plantar flexion by a new nonlinear electromyography index. The linear indices of sEMG, including the root mean square (RMS), median frequency (MF), and nonlinear index, degree centrality (DC) of the calf muscles of ten healthy male participants, were tested in the resting state and plantar flexion position to analyse their characteristics. The RMS was not normally distributed, and the MF and DC values were normally distributed. Compared with those in the resting state, the RMS, MF and DC values of all the tested muscles were significantly greater (P < 0.05) during plantar flexion. Among all the muscles, the peroneus longus (PL) changed the most. The RMS increased from 3.14 ± 1.61 µV to 49.31 ± 21.81 µV, the MF increased from 134.07 ± 30.86 Hz to 203.55 ± 28.36 Hz, and the DC changed from 2.24 ± 0.38 to 3.33 ± 0.41. Two linear indices and a nonlinear index of the PL were significantly elevated during prone plantar flexion. We speculate that the nonlinear index, DC can reflect the degree of single muscle synergistic involvement, and may become a new indicator for assessing the state of single muscle controlled by nervous system in a movement involving multiple muscles.https://doi.org/10.1038/s41598-025-09892-1Surface electromyographyNonlinear network analysisDegree centralityPlanter flexion
spellingShingle Ying Xu
Jinping Li
Xiaowen Ju
Ying Hou
Higher involvement of synergistic muscle than active muscles in ankle plantar flexion
Scientific Reports
Surface electromyography
Nonlinear network analysis
Degree centrality
Planter flexion
title Higher involvement of synergistic muscle than active muscles in ankle plantar flexion
title_full Higher involvement of synergistic muscle than active muscles in ankle plantar flexion
title_fullStr Higher involvement of synergistic muscle than active muscles in ankle plantar flexion
title_full_unstemmed Higher involvement of synergistic muscle than active muscles in ankle plantar flexion
title_short Higher involvement of synergistic muscle than active muscles in ankle plantar flexion
title_sort higher involvement of synergistic muscle than active muscles in ankle plantar flexion
topic Surface electromyography
Nonlinear network analysis
Degree centrality
Planter flexion
url https://doi.org/10.1038/s41598-025-09892-1
work_keys_str_mv AT yingxu higherinvolvementofsynergisticmusclethanactivemusclesinankleplantarflexion
AT jinpingli higherinvolvementofsynergisticmusclethanactivemusclesinankleplantarflexion
AT xiaowenju higherinvolvementofsynergisticmusclethanactivemusclesinankleplantarflexion
AT yinghou higherinvolvementofsynergisticmusclethanactivemusclesinankleplantarflexion