Assessing Postural Stability Using Coupling Strengths between Center of Pressure and Its Ground Reaction Force Components
The center of pressure (COP), which is defined as the point at which the resultant ground reaction force (GRF) is applied on a body, provides valuable information for postural stability assessment. This is because the fundamental goal of balance control is to regulate the center of mass (COM) of the...
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MDPI AG
2020-11-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/10/22/8077 |
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| author | Jia-Li Sung Lan-Yuen Guo Chin-Hsuan Liu Posen Lee Chen-Wen Yen Lih-Jiun Liaw |
| author_facet | Jia-Li Sung Lan-Yuen Guo Chin-Hsuan Liu Posen Lee Chen-Wen Yen Lih-Jiun Liaw |
| author_sort | Jia-Li Sung |
| collection | DOAJ |
| description | The center of pressure (COP), which is defined as the point at which the resultant ground reaction force (GRF) is applied on a body, provides valuable information for postural stability assessment. This is because the fundamental goal of balance control is to regulate the center of mass (COM) of the human body by adaptively changing the position of the COP. By using Newtonian mechanics to develop two equations that relate the two-dimensional COP coordinates to the GRF components, one can easily determine the location of the COP using a force plate. An important property of these two equations is that for a given COP position, there exists an infinite number of GRF component combinations that can satisfy these two equations. However, the manner in which a postural control system deals with such redundancy is still unclear. To address this redundancy problem, we introduce four postural stability features by quantifying the coupling strengths between the COP coordinates and their GRF components. Experiments involving younger (18–24 years old) and older (65–73 years) participants were conducted. The efficacy of the proposed features was demonstrated by comparing the differences between variants of each feature for each age group (18–24 and 65–73 years). The results demonstrated that the coupling strengths between the anterior–posterior (AP) direction coordinate of the COP and its GRF components for the older group were significantly higher than those of the younger group. These experimental results suggest that (1) the balance control system of the older group is more constrained than that of the younger group in coordinating the GRF components and (2) the proposed features are more sensitive to age variations than one of the most reliable and accurate conventional COP features. The best testing classification accuracy achieved by the proposed features was 0.883, whereas the testing classification accuracy achieved by the most accurate conventional COP feature was 0.777. Finally, by investigating the interactions between the COP and its GRF components using the proposed features, we found that that the AP component of the GRF of younger people plays a more active role in balance control than that of the GRF of older people. Based on these findings, it is believed that the proposed features can be used as a set of stability measures to assess the effects on posture stability from various health-related conditions such as aging and fall risk. |
| first_indexed | 2024-03-10T14:50:34Z |
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| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-03-10T14:50:34Z |
| publishDate | 2020-11-01 |
| publisher | MDPI AG |
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| series | Applied Sciences |
| spelling | doaj.art-3b022b78948840ad8e6404523cea8cfd2023-11-20T20:58:54ZengMDPI AGApplied Sciences2076-34172020-11-011022807710.3390/app10228077Assessing Postural Stability Using Coupling Strengths between Center of Pressure and Its Ground Reaction Force ComponentsJia-Li Sung0Lan-Yuen Guo1Chin-Hsuan Liu2Posen Lee3Chen-Wen Yen4Lih-Jiun Liaw5Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, TaiwanDepartment of Sports Medicine, Kaohsiung Medical University, Kaohsiung 80708, TaiwanDepartment of Occupational Therapy, Kaohsiung Municipal Kai-Syuan Psychiatric Hospital, Kaohsiung 80276, TaiwanDepartment of Occupational Therapy, I-Shou University, Kaohsiung 82245, TaiwanDepartment of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 80424, TaiwanDepartment of Physical Therapy, College of Health Science, Kaohsiung Medical University, Kaohsiung 80708, TaiwanThe center of pressure (COP), which is defined as the point at which the resultant ground reaction force (GRF) is applied on a body, provides valuable information for postural stability assessment. This is because the fundamental goal of balance control is to regulate the center of mass (COM) of the human body by adaptively changing the position of the COP. By using Newtonian mechanics to develop two equations that relate the two-dimensional COP coordinates to the GRF components, one can easily determine the location of the COP using a force plate. An important property of these two equations is that for a given COP position, there exists an infinite number of GRF component combinations that can satisfy these two equations. However, the manner in which a postural control system deals with such redundancy is still unclear. To address this redundancy problem, we introduce four postural stability features by quantifying the coupling strengths between the COP coordinates and their GRF components. Experiments involving younger (18–24 years old) and older (65–73 years) participants were conducted. The efficacy of the proposed features was demonstrated by comparing the differences between variants of each feature for each age group (18–24 and 65–73 years). The results demonstrated that the coupling strengths between the anterior–posterior (AP) direction coordinate of the COP and its GRF components for the older group were significantly higher than those of the younger group. These experimental results suggest that (1) the balance control system of the older group is more constrained than that of the younger group in coordinating the GRF components and (2) the proposed features are more sensitive to age variations than one of the most reliable and accurate conventional COP features. The best testing classification accuracy achieved by the proposed features was 0.883, whereas the testing classification accuracy achieved by the most accurate conventional COP feature was 0.777. Finally, by investigating the interactions between the COP and its GRF components using the proposed features, we found that that the AP component of the GRF of younger people plays a more active role in balance control than that of the GRF of older people. Based on these findings, it is believed that the proposed features can be used as a set of stability measures to assess the effects on posture stability from various health-related conditions such as aging and fall risk.https://www.mdpi.com/2076-3417/10/22/8077balance controlquiet standingground reaction forceforce plates |
| spellingShingle | Jia-Li Sung Lan-Yuen Guo Chin-Hsuan Liu Posen Lee Chen-Wen Yen Lih-Jiun Liaw Assessing Postural Stability Using Coupling Strengths between Center of Pressure and Its Ground Reaction Force Components Applied Sciences balance control quiet standing ground reaction force force plates |
| title | Assessing Postural Stability Using Coupling Strengths between Center of Pressure and Its Ground Reaction Force Components |
| title_full | Assessing Postural Stability Using Coupling Strengths between Center of Pressure and Its Ground Reaction Force Components |
| title_fullStr | Assessing Postural Stability Using Coupling Strengths between Center of Pressure and Its Ground Reaction Force Components |
| title_full_unstemmed | Assessing Postural Stability Using Coupling Strengths between Center of Pressure and Its Ground Reaction Force Components |
| title_short | Assessing Postural Stability Using Coupling Strengths between Center of Pressure and Its Ground Reaction Force Components |
| title_sort | assessing postural stability using coupling strengths between center of pressure and its ground reaction force components |
| topic | balance control quiet standing ground reaction force force plates |
| url | https://www.mdpi.com/2076-3417/10/22/8077 |
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