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Open Access Technical advance

Validity and reliability of the Swaymeter device for measuring postural sway

Daina L Sturnieks*, Ria Arnold and Stephen R Lord

Author Affiliations

Neuroscience Research Australia, Barker Street, Randwick, NSW, 2031, Australia

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BMC Geriatrics 2011, 11:63  doi:10.1186/1471-2318-11-63

Published: 20 October 2011

Abstract

Background

This study aimed to examine: 1) Swaymeter concurrent validity in discriminating between young and older adult populations; 2) Swaymeter convergent validity against a forceplate system; and 3) the immediate test-retest repeatability of postural sway measures obtained from the Swaymeter.

Methods

Twenty-nine older adults aged 71 to 83 years and 11 young adults aged 22 to 47 years had postural sway measured simultaneously with the Swaymeter and a forceplate for three repeat 30 second trials, under four conditions (floor eyes open, floor eyes closed, foam eyes open, foam eyes closed).

Results

Age-related differences in sway parameters across the four conditions were evident using the Swaymeter. Moderate-to-good correlations were found between Swaymeter and forceplate sway measures across conditions (r = 0.560-0.865). Good agreement between the Swaymeter and forceplate were found for anteroposterior and mediolateral sway displacement measures (average offset = 6 mm). Sway path length measures were longer for the forceplate compared to the Swaymeter (average offset = 376 mm), but these data showed good agreement following log-transformation. The Swaymeter was reliable across trials, with intraclass correlation coefficients ranging from 0.654 to 0.944.

Conclusions

The Swaymeter is a reliable tool for assessing postural sway and discriminates between performance of young and older people across multiple sensory conditions.