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The ‘Postural Rhythm’ of the Ground Reaction Force during Upright Stance and Its Conversion to Body Sway—The Effect of Vision, Support Surface and Adaptation to Repeated Trials

The ground reaction force (GRF) recorded by a platform when a person stands upright lies at the interface between the neural networks controlling stance and the body sway deduced from centre of pressure (CoP) displacement. It can be decomposed into vertical (VGRF) and horizontal (HGRF) vectors. Few...

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Autores principales: Sozzi, Stefania, Ghai, Shashank, Schieppati, Marco
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10377030/
https://www.ncbi.nlm.nih.gov/pubmed/37508910
http://dx.doi.org/10.3390/brainsci13070978
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author Sozzi, Stefania
Ghai, Shashank
Schieppati, Marco
author_facet Sozzi, Stefania
Ghai, Shashank
Schieppati, Marco
author_sort Sozzi, Stefania
collection PubMed
description The ground reaction force (GRF) recorded by a platform when a person stands upright lies at the interface between the neural networks controlling stance and the body sway deduced from centre of pressure (CoP) displacement. It can be decomposed into vertical (VGRF) and horizontal (HGRF) vectors. Few studies have addressed the modulation of the GRFs by the sensory conditions and their relationship with body sway. We reconsidered the features of the GRFs oscillations in healthy young subjects (n = 24) standing for 90 s, with the aim of characterising the possible effects of vision, support surface and adaptation to repeated trials, and the correspondence between HGRF and CoP time-series. We compared the frequency spectra of these variables with eyes open or closed on solid support surface (EOS, ECS) and on foam (EOF, ECF). All stance trials were repeated in a sequence of eight. Conditions were randomised across different days. The oscillations of the VGRF, HGRF and CoP differed between each other, as per the dominant frequency of their spectra (around 4 Hz, 0.8 Hz and <0.4 Hz, respectively) featuring a low-pass filter effect from VGRF to HGRF to CoP. GRF frequencies hardly changed as a function of the experimental conditions, including adaptation. CoP frequencies diminished to <0.2 Hz when vision was available on hard support surface. Amplitudes of both GRFs and CoP oscillations decreased in the order ECF > EOF > ECS ≈ EOS. Adaptation had no effect except in ECF condition. Specific rhythms of the GRFs do not transfer to the CoP frequency, whereas the magnitude of the forces acting on the ground ultimately determines body sway. The discrepancies in the time-series of the HGRF and CoP oscillations confirm that the body’s oscillation mode cannot be dictated by the inverted pendulum model in any experimental conditions. The findings emphasise the robustness of the VGRF “postural rhythm” and its correspondence with the cortical theta rhythm, shed new insight on current principles of balance control and on understanding of upright stance in healthy and elderly people as well as on injury prevention and rehabilitation.
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spelling pubmed-103770302023-07-29 The ‘Postural Rhythm’ of the Ground Reaction Force during Upright Stance and Its Conversion to Body Sway—The Effect of Vision, Support Surface and Adaptation to Repeated Trials Sozzi, Stefania Ghai, Shashank Schieppati, Marco Brain Sci Article The ground reaction force (GRF) recorded by a platform when a person stands upright lies at the interface between the neural networks controlling stance and the body sway deduced from centre of pressure (CoP) displacement. It can be decomposed into vertical (VGRF) and horizontal (HGRF) vectors. Few studies have addressed the modulation of the GRFs by the sensory conditions and their relationship with body sway. We reconsidered the features of the GRFs oscillations in healthy young subjects (n = 24) standing for 90 s, with the aim of characterising the possible effects of vision, support surface and adaptation to repeated trials, and the correspondence between HGRF and CoP time-series. We compared the frequency spectra of these variables with eyes open or closed on solid support surface (EOS, ECS) and on foam (EOF, ECF). All stance trials were repeated in a sequence of eight. Conditions were randomised across different days. The oscillations of the VGRF, HGRF and CoP differed between each other, as per the dominant frequency of their spectra (around 4 Hz, 0.8 Hz and <0.4 Hz, respectively) featuring a low-pass filter effect from VGRF to HGRF to CoP. GRF frequencies hardly changed as a function of the experimental conditions, including adaptation. CoP frequencies diminished to <0.2 Hz when vision was available on hard support surface. Amplitudes of both GRFs and CoP oscillations decreased in the order ECF > EOF > ECS ≈ EOS. Adaptation had no effect except in ECF condition. Specific rhythms of the GRFs do not transfer to the CoP frequency, whereas the magnitude of the forces acting on the ground ultimately determines body sway. The discrepancies in the time-series of the HGRF and CoP oscillations confirm that the body’s oscillation mode cannot be dictated by the inverted pendulum model in any experimental conditions. The findings emphasise the robustness of the VGRF “postural rhythm” and its correspondence with the cortical theta rhythm, shed new insight on current principles of balance control and on understanding of upright stance in healthy and elderly people as well as on injury prevention and rehabilitation. MDPI 2023-06-21 /pmc/articles/PMC10377030/ /pubmed/37508910 http://dx.doi.org/10.3390/brainsci13070978 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Sozzi, Stefania
Ghai, Shashank
Schieppati, Marco
The ‘Postural Rhythm’ of the Ground Reaction Force during Upright Stance and Its Conversion to Body Sway—The Effect of Vision, Support Surface and Adaptation to Repeated Trials
title The ‘Postural Rhythm’ of the Ground Reaction Force during Upright Stance and Its Conversion to Body Sway—The Effect of Vision, Support Surface and Adaptation to Repeated Trials
title_full The ‘Postural Rhythm’ of the Ground Reaction Force during Upright Stance and Its Conversion to Body Sway—The Effect of Vision, Support Surface and Adaptation to Repeated Trials
title_fullStr The ‘Postural Rhythm’ of the Ground Reaction Force during Upright Stance and Its Conversion to Body Sway—The Effect of Vision, Support Surface and Adaptation to Repeated Trials
title_full_unstemmed The ‘Postural Rhythm’ of the Ground Reaction Force during Upright Stance and Its Conversion to Body Sway—The Effect of Vision, Support Surface and Adaptation to Repeated Trials
title_short The ‘Postural Rhythm’ of the Ground Reaction Force during Upright Stance and Its Conversion to Body Sway—The Effect of Vision, Support Surface and Adaptation to Repeated Trials
title_sort ‘postural rhythm’ of the ground reaction force during upright stance and its conversion to body sway—the effect of vision, support surface and adaptation to repeated trials
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10377030/
https://www.ncbi.nlm.nih.gov/pubmed/37508910
http://dx.doi.org/10.3390/brainsci13070978
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