The effects of optic flow on postural stability: Influence of age and fall risk.

Humans Aged Optic Flow Posture Muscle, Skeletal / physiology Postural Balance / physiology Standing Position
Accidental falls Aged Optic flow Postural sway Posture Visual field dependence

Journal

Experimental gerontology
ISSN: 1873-6815
Titre abrégé: Exp Gerontol
Pays: England
ID NLM: 0047061

Informations de publication

Date de publication:
05 2023
Historique:
received: 13 10 2022
revised: 05 02 2023
accepted: 13 03 2023
medline: 18 4 2023
pubmed: 17 3 2023
entrez: 16 3 2023
Statut: ppublish

Résumé

Optic flow provides dynamic information relating to body position and motion with respect to visual frames of reference. This study investigated the effects of optic flow stimuli presented in four directions on postural stability in young and older adults. Twenty-five young (20-40 years) and 51 older (≥65 years) people participated in this study, with the older group classified into low fall risk (n = 27), and high fall risk (n = 24) sub-groups. While standing in a dark room, participants viewed static scattered white dots for 30 s, followed by 30 s periods of optic flow consisting of white dots "moving" in one of four flow directions, randomised: radial expansion and contraction, circular anti-clockwise and clockwise. Centre of pressure (CoP) position, postural sway in anteroposterior (AP) and mediolateral (ML) axes, and muscle activity of tibialis anterior (TA), gastrocnemius medialis (GM) and tensor fascia latae (TFL) were recorded. Across groups, the four optic flow stimuli induced increased AP sway and three of the four optic flow stimuli induced increased ML sway, with concomitant increases in muscle activity, indicating optic flow stimuli induced a generalised destabilising, rather than a direction-specific, effect. Only one optic flow condition (radial contraction) induced a change in average CoP position, and this may reflect the adoption of a protective stance position to avoid a backward fall. Optic flow destabilised postural control more in older people compared with younger people, and radial expansion stimuli destabilised ML postural control more in the older high fall risk group compared with the older low fall risk group. Optic flow stimuli have a generalised destabilising effect on postural control across groups as shown by non-directional specific increases in postural sway and muscular activity. Optic flow stimuli have a greater impact on postural stability in older compared with younger adults and this is more pronounced in the ML plane for older people at increased risk of falls.

Sections du résumé

BACKGROUND
Optic flow provides dynamic information relating to body position and motion with respect to visual frames of reference. This study investigated the effects of optic flow stimuli presented in four directions on postural stability in young and older adults.
METHODS
Twenty-five young (20-40 years) and 51 older (≥65 years) people participated in this study, with the older group classified into low fall risk (n = 27), and high fall risk (n = 24) sub-groups. While standing in a dark room, participants viewed static scattered white dots for 30 s, followed by 30 s periods of optic flow consisting of white dots "moving" in one of four flow directions, randomised: radial expansion and contraction, circular anti-clockwise and clockwise. Centre of pressure (CoP) position, postural sway in anteroposterior (AP) and mediolateral (ML) axes, and muscle activity of tibialis anterior (TA), gastrocnemius medialis (GM) and tensor fascia latae (TFL) were recorded.
RESULTS
Across groups, the four optic flow stimuli induced increased AP sway and three of the four optic flow stimuli induced increased ML sway, with concomitant increases in muscle activity, indicating optic flow stimuli induced a generalised destabilising, rather than a direction-specific, effect. Only one optic flow condition (radial contraction) induced a change in average CoP position, and this may reflect the adoption of a protective stance position to avoid a backward fall. Optic flow destabilised postural control more in older people compared with younger people, and radial expansion stimuli destabilised ML postural control more in the older high fall risk group compared with the older low fall risk group.
CONCLUSION
Optic flow stimuli have a generalised destabilising effect on postural control across groups as shown by non-directional specific increases in postural sway and muscular activity. Optic flow stimuli have a greater impact on postural stability in older compared with younger adults and this is more pronounced in the ML plane for older people at increased risk of falls.

Identifiants

DOI: 10.1016/j.exger.2023.112146 PMID: 36925085
pubmed: 36925085
pii: S0531-5565(23)00067-0
doi: 10.1016/j.exger.2023.112146
pii:
doi:

Types de publication

Journal Article Research Support, Non-U.S. Gov't

Langues

eng

Sous-ensembles de citation

IM

Pagination

112146

Informations de copyright

Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.

Déclaration de conflit d'intérêts

Conflicts of interest The authors have no conflicts of interest to declare.

Auteurs

Steven Phu (S)

Falls, Balance and Injury Research Centre, Neuroscience Research Australia, Randwick, NSW, Australia; School of Population Health, The University of New South Wales, Sydney, NSW, Australia; Department of Medicine, Western Health, The University of Melbourne, St Albans, VIC, Australia.

Michela Persiani (M)

Falls, Balance and Injury Research Centre, Neuroscience Research Australia, Randwick, NSW, Australia; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.

Brandon Tan (B)

Falls, Balance and Injury Research Centre, Neuroscience Research Australia, Randwick, NSW, Australia; School of Population Health, The University of New South Wales, Sydney, NSW, Australia.

Matthew Brodie (M)

Falls, Balance and Injury Research Centre, Neuroscience Research Australia, Randwick, NSW, Australia; School of Population Health, The University of New South Wales, Sydney, NSW, Australia.

Simon Gandevia (S)

Falls, Balance and Injury Research Centre, Neuroscience Research Australia, Randwick, NSW, Australia; School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia.

Daina L Sturnieks (DL)

Falls, Balance and Injury Research Centre, Neuroscience Research Australia, Randwick, NSW, Australia; School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia.

Stephen R Lord (SR)

Falls, Balance and Injury Research Centre, Neuroscience Research Australia, Randwick, NSW, Australia; School of Population Health, The University of New South Wales, Sydney, NSW, Australia. Electronic address: s.lord@neura.edu.au.

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Classifications MeSH

questionsmedicales.fr › Eucaryotes › Animaux › Chordés › Vertébrés › Mammifères › Eutheria › Primates › Haplorhini › Catarrhini › Hominidae › Humains › The effects of optic flow on postural...
questionsmedicales.fr › Personnes › Tranches d'âge › Adulte › Sujet âgé › The effects of optic flow on postural...
questionsmedicales.fr › Phénomènes physiologiques oculaires › Flux optique › The effects of optic flow on postural...
questionsmedicales.fr › Phénomènes physiologiques de l'appareil locomoteur et du système nerveux › Phénomènes physiologiques du système locomoteur › Posture › The effects of optic flow on postural...
questionsmedicales.fr › Tissus › Muscles › Muscle strié › Muscles squelettiques › The effects of optic flow on postural...
questionsmedicales.fr › Phénomènes physiologiques de l'appareil locomoteur et du système nerveux › Phénomènes physiologiques du système nerveux › Sensation › Proprioception › Équilibre postural › The effects of optic flow on postural...
questionsmedicales.fr › Phénomènes physiologiques de l'appareil locomoteur et du système nerveux › Phénomènes physiologiques du système locomoteur › Posture › Position debout › The effects of optic flow on postural...