Acoustic pre-stimulation modulates startle and postural reactions during sudden release of standing support surface in aging.

Autor: Hsiao H; Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX, USA., Creath RA; Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Exercise Science, Lebanon Valley College, Annville, PA, USA., Sanders O; Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD, USA; Division of Neurological and Physical Medicine Devices, Office of Device Evaluation, Center for Devices and Radiological Health, United States Food and Drug Administration, Silver Spring, MD, USA., Inacio M; Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD, USA; Research Center in Sports Sciences, Health Sciences and Human Development, University Institute of Maia, Portugal., Beamer BA; Gerontology Research, Education and Clinical Center (GRECC) at Baltimore Veterans Affairs Medical Center, Division of Gerontology and Geriatric Medicine, University of Maryland School of Medicine, Baltimore, MD, USA., Rogers MW; Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD, USA. Electronic address: mwrogers@som.umaryland.edu.
Jazyk: angličtina
Zdroj: Human movement science [Hum Mov Sci] 2020 Dec; Vol. 74, pp. 102715. Date of Electronic Publication: 2020 Nov 20.
DOI: 10.1016/j.humov.2020.102715
Abstrakt: Falls contribute to injuries and reduced level of physical activity in older adults. During falls, the abrupt sensation of moving downward triggers a startle-like reaction that may interfere with protective response movements necessary to maintain balance. Startle reaction could be dampened by sensory pre-stimulation delivered immediately before a startling stimulus. This study investigated the neuromodulatory effects of pre-stimulation on postural/startle responses to drop perturbations of the standing support surface in relation to age. Ten younger and 10 older adults stood quietly on an elevated computer-controlled moveable platform. At an unpredictable time, participants were dropped vertically to elicit a startle-like response. Reactive drop perturbation trials without a pre-stimulus (control) were alternated with trials with acoustic pre-stimulus tone (PSI). A two-way mixed design analysis of variance comparing condition (control vs. PSI) X group (younger vs. older) was performed to analyze changes in muscle activation patterns, ground reaction force, and joint angular displacements. Compared to younger adults, older adults showed lower neck muscle electromyography amplitude reduction rate and incidence of response. Peak muscle activation in neck, upper arm, and hamstring muscles were reduced during PSI trials compared to control trials in both groups (p < 0.05). In addition, knee and hip joint flexion prior to ground contact was reduced in PSI trials compared to control (p < 0.05). During post-landing balance recovery, increased knee and hip flexion displacement and time to peak impact force were observed in PSI trials compared to control condition (p < 0.05). PSI reduced startle-induced muscle activation at proximal body segments and likely decreased joint flexion during abrupt downward vertical displacement perturbations of the body. Older adults retained the ability to modulate startle and postural responses but their neuromodulatory capacity was reduced compared with younger adults. Further research on the potential of applying PSI as a possible therapeutic tool to reduce the risk of fall-related injury is needed.
(Copyright © 2020. Published by Elsevier B.V.)
Databáze: MEDLINE
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