The postural control under falls simulated visual inputs during stepping down in the elderly subjects : a pilot study

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The postural control under falls simulated visual inputs during stepping down in the elderly subjects : a pilot study


Author: Chan, Vivien
Title: The postural control under falls simulated visual inputs during stepping down in the elderly subjects : a pilot study
Year: 2004
Subject: Hong Kong Polytechnic University -- Dissertations
Falls (Accidents) in old age -- Prevention
Human mechanics
Equilibrium (Physiology)
Department: Dept. of Rehabilitation Sciences
Pages: x, 63 leaves : col. ill. ; 30 cm
Language: English
InnoPac Record:
Abstract: Hong Kong has an increasing aging population. Falls is the common cause of injury among elderly people. Deterioration in postural control is one of the major causes of falls. Good postural control depends on integration of sensory inputs with coordinated motor response. Somatosensory, visual and vestibular systems provide sensory inputs to the central nervous system. When one sensory system is not providing optimal or accurate information, the weight given to that sensory modality is reduced, while the weight of sensory modalities providing more accurate information is increased to maintain postural control. The process of selecting and integrating appropriate sensory information was termed sensory organization. With aging, research has shown that deterioration of the process of sensory organization contributes to an increased likelihood of falls. How the elderly subjects tackle the pre-landing leg muscle coordination during a stepping down activity under falls simulated visual input remains unknown. In this pilot study, 9 elderly subjects (mean age = 66.9 +- 6.2 years) and 9 young subjects (mean age = 22.6 +- 5.0 years) were recruited. The muscle activities of the pre-landing leg with and without falls simulated visual conditions during stepping down were investigated. Subjects received the falls simulated visual input simulating "virtual falls" through a visual display unit in form of a pair of goggles. The pre-landing muscle activities of tibialis anterior (TA) and medial gastrocnemius (MG) of subjects' dominant leg during stepping down from a 6 inch platform at self selected speeds were measured. Results from this study might provide a better insight in the effects of visual inputs on postural control during a functional movement. Our results demonstrated that the pre-landing muscle activities of the TA and MG achieved satisfactory reliability with ICC ranged from 0.83 to 0.88 in the elderly subjects. Both the pre-landing response latencies of TA and MG under the subjects wearing goggles with and without fall simulated visual inputs between the elderly and young groups were not significantly different. In comparing the pre-landing response latency of TA and MG with and without falls simulated visual inputs in elderly people, there was a significant difference on the pre-landing response latency of MG in elderly subjects. Under falls simulated visual inputs during stepping down, elderly subjects had longer pre-landing response latency in MG. (376 words).

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