A Comprehensive Understanding of Postural Tone Biomechanics: Intrinsic Stiffness, Functional Stiffness, Antagonist Coactivation, and COP Dynamics in Post-Stroke Adults
Objective: To analyse the relationship between traditional stiffness and muscle antagonist coactivation in both stroke and healthy participants, using linear and non-linear measures of coactivation and COP during standing, stand-to-sit, and gait initiation. Methods: Participants were evaluated throu...
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2025-03-01
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| author | Liliana Pinho Marta Freitas Francisco Pinho Sandra Silva Vânia Figueira Edgar Ribeiro Andreia S. P. Sousa Filipa Sousa Augusta Silva |
| author_facet | Liliana Pinho Marta Freitas Francisco Pinho Sandra Silva Vânia Figueira Edgar Ribeiro Andreia S. P. Sousa Filipa Sousa Augusta Silva |
| author_sort | Liliana Pinho |
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| description | Objective: To analyse the relationship between traditional stiffness and muscle antagonist coactivation in both stroke and healthy participants, using linear and non-linear measures of coactivation and COP during standing, stand-to-sit, and gait initiation. Methods: Participants were evaluated through a cross-sectional design. Electromyography, isokinetic dynamometer, and force plate were used to calculate coactivation, intrinsic and functional stiffness, and COP displacement, with both linear and non-linear metrics. Spearman’s correlations and Mann–Whitney tests were applied (<i>p</i> < 0.05). Results: Post-stroke participants showed higher contralesional intrinsic stiffness (<i>p</i> = 0.041) and higher functional stiffness (<i>p</i> = 0.047). Coactivation was higher on the ipsilesional side during standing (<i>p</i> = 0.012) and reduced on the contralesional side during standing and transitions (<i>p</i> < 0.01). Moderate correlations were found between intrinsic and functional stiffness (<i>p</i> = 0.030) and between coactivation and intrinsic stiffness (standing and stand-to-sit: <i>p</i> = 0.048) and functional stiffness (gait initiation: <i>p</i> = 0.045). COP displacement was reduced in post-stroke participants during standing (<i>p</i> < 0.001) and increased during gait initiation (<i>p</i> = 0.001). Post-stroke participants exhibited increased gastrocnemius/tibialis anterior coactivation during gait initiation (<i>p</i> = 0.038) and higher entropy and stability across tasks (<i>p</i> < 0.001). Conclusion: Post-stroke participants showed higher contralesional intrinsic and functional stiffness, reduced coactivation in static tasks, and increased coactivation in dynamic tasks. COP and coactivation analyses revealed impaired stability and random control, highlighting the importance of multidimensional evaluations of postural tone. |
| format | Article |
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| institution | DOAJ |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
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| series | Sensors |
| spelling | doaj-art-c39715d18ab94dc9ac0502a4d716e5542025-08-20T03:03:23ZengMDPI AGSensors1424-82202025-03-01257219610.3390/s25072196A Comprehensive Understanding of Postural Tone Biomechanics: Intrinsic Stiffness, Functional Stiffness, Antagonist Coactivation, and COP Dynamics in Post-Stroke AdultsLiliana Pinho0Marta Freitas1Francisco Pinho2Sandra Silva3Vânia Figueira4Edgar Ribeiro5Andreia S. P. Sousa6Filipa Sousa7Augusta Silva8Escola Superior de Saúde do Vale do Ave, Cooperativa de Ensino Superior Politécnico e Universitário, Rua José António Vidal, 81, 4760-409 Vila Nova de Famalicão, PortugalEscola Superior de Saúde do Vale do Ave, Cooperativa de Ensino Superior Politécnico e Universitário, Rua José António Vidal, 81, 4760-409 Vila Nova de Famalicão, PortugalEscola Superior de Saúde do Vale do Ave, Cooperativa de Ensino Superior Politécnico e Universitário, Rua José António Vidal, 81, 4760-409 Vila Nova de Famalicão, PortugalEscola Superior de Saúde do Vale do Ave, Cooperativa de Ensino Superior Politécnico e Universitário, Rua José António Vidal, 81, 4760-409 Vila Nova de Famalicão, PortugalEscola Superior de Saúde do Vale do Ave, Cooperativa de Ensino Superior Politécnico e Universitário, Rua José António Vidal, 81, 4760-409 Vila Nova de Famalicão, PortugalCentre of Research Rehabilitation (CIR), Escola Superior de Saúde, rua Dr. António Bernardino de Almeida 400, 4200-072 Porto, PortugalCentre of Research Rehabilitation (CIR), Escola Superior de Saúde, rua Dr. António Bernardino de Almeida 400, 4200-072 Porto, PortugalCentre for Research, Education, Innovation, and Intervention in Sport (CIFI2D), Faculty of Sport of the University of Porto (FADEUP), 4050-313 Porto, PortugalCentre of Research Rehabilitation (CIR), Escola Superior de Saúde, rua Dr. António Bernardino de Almeida 400, 4200-072 Porto, PortugalObjective: To analyse the relationship between traditional stiffness and muscle antagonist coactivation in both stroke and healthy participants, using linear and non-linear measures of coactivation and COP during standing, stand-to-sit, and gait initiation. Methods: Participants were evaluated through a cross-sectional design. Electromyography, isokinetic dynamometer, and force plate were used to calculate coactivation, intrinsic and functional stiffness, and COP displacement, with both linear and non-linear metrics. Spearman’s correlations and Mann–Whitney tests were applied (<i>p</i> < 0.05). Results: Post-stroke participants showed higher contralesional intrinsic stiffness (<i>p</i> = 0.041) and higher functional stiffness (<i>p</i> = 0.047). Coactivation was higher on the ipsilesional side during standing (<i>p</i> = 0.012) and reduced on the contralesional side during standing and transitions (<i>p</i> < 0.01). Moderate correlations were found between intrinsic and functional stiffness (<i>p</i> = 0.030) and between coactivation and intrinsic stiffness (standing and stand-to-sit: <i>p</i> = 0.048) and functional stiffness (gait initiation: <i>p</i> = 0.045). COP displacement was reduced in post-stroke participants during standing (<i>p</i> < 0.001) and increased during gait initiation (<i>p</i> = 0.001). Post-stroke participants exhibited increased gastrocnemius/tibialis anterior coactivation during gait initiation (<i>p</i> = 0.038) and higher entropy and stability across tasks (<i>p</i> < 0.001). Conclusion: Post-stroke participants showed higher contralesional intrinsic and functional stiffness, reduced coactivation in static tasks, and increased coactivation in dynamic tasks. COP and coactivation analyses revealed impaired stability and random control, highlighting the importance of multidimensional evaluations of postural tone.https://www.mdpi.com/1424-8220/25/7/2196muscle tonepostural controlneuromuscular adaptationnon-linear analysisbiomechanical stability |
| spellingShingle | Liliana Pinho Marta Freitas Francisco Pinho Sandra Silva Vânia Figueira Edgar Ribeiro Andreia S. P. Sousa Filipa Sousa Augusta Silva A Comprehensive Understanding of Postural Tone Biomechanics: Intrinsic Stiffness, Functional Stiffness, Antagonist Coactivation, and COP Dynamics in Post-Stroke Adults Sensors muscle tone postural control neuromuscular adaptation non-linear analysis biomechanical stability |
| title | A Comprehensive Understanding of Postural Tone Biomechanics: Intrinsic Stiffness, Functional Stiffness, Antagonist Coactivation, and COP Dynamics in Post-Stroke Adults |
| title_full | A Comprehensive Understanding of Postural Tone Biomechanics: Intrinsic Stiffness, Functional Stiffness, Antagonist Coactivation, and COP Dynamics in Post-Stroke Adults |
| title_fullStr | A Comprehensive Understanding of Postural Tone Biomechanics: Intrinsic Stiffness, Functional Stiffness, Antagonist Coactivation, and COP Dynamics in Post-Stroke Adults |
| title_full_unstemmed | A Comprehensive Understanding of Postural Tone Biomechanics: Intrinsic Stiffness, Functional Stiffness, Antagonist Coactivation, and COP Dynamics in Post-Stroke Adults |
| title_short | A Comprehensive Understanding of Postural Tone Biomechanics: Intrinsic Stiffness, Functional Stiffness, Antagonist Coactivation, and COP Dynamics in Post-Stroke Adults |
| title_sort | comprehensive understanding of postural tone biomechanics intrinsic stiffness functional stiffness antagonist coactivation and cop dynamics in post stroke adults |
| topic | muscle tone postural control neuromuscular adaptation non-linear analysis biomechanical stability |
| url | https://www.mdpi.com/1424-8220/25/7/2196 |
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