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Losing control and developing concerns: The complexities of ageing postural control and fall-related concerns
Luleå University of Technology, Department of Health, Learning and Technology, Health, Medicine and Rehabilitation.ORCID iD: 0000-0002-2510-7571
2021 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Att tappa kontrollen och utveckla oro : Komplexiteterna av åldrande postural kontroll och fall-relaterad oro (Swedish)
Abstract [en]

With the world population shifting its proportions towards higher ages, it is imperative to increase healthspan rather than lifespan, both for the sakes of community sustainability as well as individual quality of life. One of the main means to obtain healthy ageing, is a concept called active ageing, as activity has shown to slow down the natural ageing process. 

Active ageing is threatened by a decline in balance performance and an increase of fall-related concerns, as activity curtailment is a major consequence. Fall-related concerns are prevalent in a large portion of the older population. Current understanding of its mechanisms is largely hypothesised, based on few observational studies in which single factors – mostly psychological – are researched. Postural control is the system that helps us maintain balance and control while moving or being still. Yet, the interactions between fall-related concerns and postural control are not very well described. Sensory input and processing have been identified as possibly an important part, but more in-depth investigations are needed.

To investigate the prevalence and factors that may play a part in fall-related concerns, 153 older adults (70 years and over) were visited in their home. During these visits questionnaires and clinical tests were administered (among them FES-I, PGCM, SPPB, MMSE). To investigate the relationship between fall-related concerns and postural control more thoroughly, 45 of the original sample were also tested in the movement laboratory. Several modalities of sensory function were recorded, as well as lower limb strength and quiet stance centre of pressure. 

The home visits showed that 70% of people 70 years and older, living in the community experience at least one of the constructs of fall-related concerns and that associated factors are of both psychological and physical nature (fear, morale, and physical performance). Large and significant differences between men and women were discovered not only in prevalence, but also for the associated factors. Hierarchical multivariate modelling of the laboratory data showed that an increase in sway size and velocity during open eyes quiet stance can explain a rise in fall-related concerns and that that relationship in turn can be explained by declines in specific parts of the postural control system (lower limb strength, reaction time, vision, and proprioception of the ankle, knee, and neck). The more in-depth methods of frequency domain and multivariate discriminant analysis revealed that older participants could be grouped in ‘declined and concerned’ and ‘not declined and not concerned.’ The first showing power in lower frequencies of the postural sway signal than the latter and showing an inability to adjust control strategy when closing their eyes. Finally, the changing and adapting postural control of older people was successfully modelled by applying dimension reduction, neural networks, and an internal feedback of 150ms. The model can predict postural corrections up to 1 second ahead of time. This gave more insight in key features of successful adaptation to an ageing system and provides a virtual environment for future model and theory testing. 

In conclusion, I have gained more understanding of the complexity and interaction of the different systems involved in the concern-and-balance relationship and have contributed to the field by showing methods that will improve the quality of analyses when testing, evaluating, and researching these phenomena. 

Place, publisher, year, edition, pages
Luleå University of Technology, 2021.
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords [en]
ageing, postural balance, postural control, sensory and motor systems, fall-related concerns, fear of falling, neurological models
National Category
Physiotherapy
Research subject
Physiotherapy
Identifiers
URN: urn:nbn:se:ltu:diva-83195ISBN: 978-91-7790-775-6 (print)ISBN: 978-91-7790-776-3 (electronic)OAI: oai:DiVA.org:ltu-83195DiVA, id: diva2:1535096
Public defence
2021-05-20, E632 / Zoom, Luleå, 09:00 (English)
Opponent
Supervisors
Projects
BAHRT
Funder
Swedish Research Council, K2015-99X-22756-01-4Available from: 2021-03-08 Created: 2021-03-08 Last updated: 2023-09-05Bibliographically approved
List of papers
1. Both psychological factors and physical performance are associated with fall-related concerns
Open this publication in new window or tab >>Both psychological factors and physical performance are associated with fall-related concerns
2018 (English)In: Aging Clinical and Experimental Research, ISSN 1594-0667, E-ISSN 1720-8319, Vol. 30, no 9, p. 1079-1085Article in journal (Refereed) Published
Abstract [en]

Background Fall-related concern strongly correlates to activity avoidance in older people.  In this complex phenomenon, different terminology and instruments are often used interchangeably. Three main concepts make up fall-related concerns: fear-of-falling, consequence concern, and falls self-efficacy. It is suggested that fall-related concerns are mediated by psychological and physical factors.

Aims Our aims were to describe the prevalence of fall-related concerns and find explanatory factors for its most studied concept – falls self-efficacy – in an older population.

Methods We executed a cross sectional study on a random sample of 153 community dwelling older people (70 years or older). We used validated and reliable instruments as well as structured interviews to gather data on the three concepts of fall-related concerns and possible mediating factors. We then calculated descriptive statistics on prevalence and regression models for the total group, and men and women separately.

Results 70% of the total sample (80% of women and 53% of men) reported at least one of the three concepts of fall-related concern. For the total sample, fear-of-falling, morale and physical performance were associated factors with falls self-efficacy. For women, number of prescription medications was added. For men, physical performance and concerns for injury were associated.

Conclusion Fall-related concern is prevalent in large proportions with higher prevalence for women than for men. Important factors are fear of falling, morale, and physical performance. Gender differences in the emergence and variance of fall-related concern and the relation between physical performance and fall-related concern should be targeted in future research endeavors. 

Place, publisher, year, edition, pages
Springer, 2018
Keywords
aged, fall-related concerns, morale, ambulation, self-efficacy
National Category
Physiotherapy
Research subject
Physiotherapy
Identifiers
urn:nbn:se:ltu:diva-67031 (URN)10.1007/s40520-017-0882-9 (DOI)000441365800008 ()29264814 (PubMedID)2-s2.0-85038615621 (Scopus ID)
Projects
BAHRT
Note

Validerad;2018;Nivå 2;2018-08-17 (andbra)

Available from: 2017-12-15 Created: 2017-12-15 Last updated: 2023-09-05Bibliographically approved
2. Decline in sensorimotor systems explains reduced falls self-efficacy
Open this publication in new window or tab >>Decline in sensorimotor systems explains reduced falls self-efficacy
Show others...
2018 (English)In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 42, p. 104-110Article in journal (Refereed) Published
Abstract [en]

Physical performance including balance tasks is one of the main factors explaining the variance in falls self-efficacy in older adults. Balance performance is often measured by use of gross assessment scales, which assess the result of integration of all systems involved in postural control. We aimed to investigate which measurements of postural control correlate to falls self-efficacy scores as measured by the FES-I instrument, and which sensory and motor systems best explain them. A cross sectional study was designed, in which 45 older adults performed quiet stance and limits of stability trials during which their center of pressure (CoP) excursion was recorded. Falls self-efficacy was measured using the Falls Efficacy Scale - International. Eyesight, vestibular function, proprioception, reaction time and strength were also measured. Hierarchical orthogonal projection of latent structures was used to model FES-I with the CoP trials and then with the sensory and muscle function data. Fes-I could be explained to 39%, with the eyes open trials and the limits of stability trials loading the heaviest. The base model could be explained to 40% using the sensory and muscle function data, with lower limb strength, leg proprioception, neck proprioception, reaction time and eyesight loading the heaviest.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Physiotherapy
Research subject
Physiotherapy
Identifiers
urn:nbn:se:ltu:diva-70143 (URN)10.1016/j.jelekin.2018.07.001 (DOI)000441876400013 ()30015133 (PubMedID)2-s2.0-85049755548 (Scopus ID)
Projects
BAHRT
Note

Validerad;2018;Nivå 2;2018-08-08 (andbra)

Available from: 2018-07-20 Created: 2018-07-20 Last updated: 2021-03-08Bibliographically approved
3. Frequency domain shows: Fall-related concerns and sensorimotor decline explain inability to adjust postural control strategy in older adults
Open this publication in new window or tab >>Frequency domain shows: Fall-related concerns and sensorimotor decline explain inability to adjust postural control strategy in older adults
Show others...
2020 (English)In: PLOS ONE, E-ISSN 1932-6203, Vol. 15, no 11, article id e0242608Article in journal (Refereed) Published
Abstract [en]

Human postural control is a complex system and changes as we age. Frequency based analyses have been argued to be useful to identify altered postural control strategies in balance tasks. The aim of this study was to explore the frequency domain of the quiet stance centre of pressure of older adults with various degrees of fall-related concerns and sensorimotor functioning. We included 45 community dwelling older adults and used a force plate to register 30 seconds of quiet stance with eyes open and closed respectively. We also measured sensory and motor functions, as well as fall-related concerns and morale. We analysed the centre of pressure power spectrum density and extracted the frequency of 4 of its features for each participant. Orthogonal projection of latent structures–discriminant analysis revealed two groups for each quiet stance trial. Group 1 of each trial showed less sensory and motor decline, low/no fall-related concerns and higher frequencies. Group 2 showed more decline, higher fall-related concerns and lower frequencies. During the closed eyes trial, group 1 and group 2 shifted their features to higher frequencies, but only group 1 did so in any significant way. Higher fall-related concerns, sensory and motor decline, and explorative balancing strategies are highly correlated. The control system of individuals experiencing this seems to be highly dependent on vision. Higher fall-related concerns, and sensory and motor decline are also correlated with the inability to adjust to faster, more reactive balancing strategies, when vision is not available.

Place, publisher, year, edition, pages
PLOS, 2020
National Category
Physiotherapy Control Engineering
Research subject
Physiotherapy; Automatic Control
Identifiers
urn:nbn:se:ltu:diva-81577 (URN)10.1371/journal.pone.0242608 (DOI)000595653500011 ()33216812 (PubMedID)2-s2.0-85096771049 (Scopus ID)
Projects
BAHRT
Funder
Swedish Research Council, K2015-99X-22756-01-4
Note

Validerad;2020;Nivå 2;2020-11-24 (alebob)

Available from: 2020-11-24 Created: 2020-11-24 Last updated: 2023-09-05Bibliographically approved
4. On Internal Modeling of the Upright Postural Control in Elderly
Open this publication in new window or tab >>On Internal Modeling of the Upright Postural Control in Elderly
Show others...
2018 (English)In: IEEE ROBIO 2018, IEEE, 2018, p. 231-236Conference paper, Published paper (Refereed)
Abstract [en]

The second most common cause of injury in the elderly population is falling. In an effort to understand the mechanism behind the reduced ability to maintain balance in any posture or activity, we study the performance of the central nervous system as a controller of the body, while maintaining the balance in some postures or activities. Towards this direction, forty-five subjects aged over 70 were tested in different trials of quiet stance: a) hard stable surface with open eyes, b) stable surface with closed eyes, c) soft unstable surface with open eyes, and d) unstable surface, while eyes were closed. In the sequel, the body kinematics were described by legs and trunk segment angles in the sagittal plane, while the muscle activations were described by a weighted sum of rectified EMG signals from tibialis anterior and gastrocnemius muscles of left and right legs. Using the neuro-science hypothesis and adaptive control theory, a completely novel model was identified for the CNS based on the feedback internal model. The proposed model is able to predict the output commands, based on a recurrent neural network, while the efficiency of the proposed scheme has been proven based on multiple experimental results, showing that the model can sufficiently predict the muscle activity based on the optimum sensory inputs.

Place, publisher, year, edition, pages
IEEE, 2018
Series
IEEE International Conference on Robotics and Biomimetics
National Category
Control Engineering Physiotherapy
Research subject
Control Engineering; Physiotherapy
Identifiers
urn:nbn:se:ltu:diva-72472 (URN)10.1109/ROBIO.2018.8665209 (DOI)000468772200036 ()2-s2.0-85064111622 (Scopus ID)
Conference
2018 IEEE International Conference on Robotics and Biomimetics (ROBIO),12-15 December, 2018, Kuala Lumpur, Malaysia
Projects
BAHRT
Note

ISBN för värdpublikation: 978-1-7281-0377-8, 978-1-7281-0378-5

Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2023-09-05Bibliographically approved

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