TEST–RETEST RELIABILITY OF POSTURAL SWAY MEASURES DURING STATIC STANDING BALANCE PERFORMANCE IN HEALTHY ELDERLY ADULTS

Abstract

Little is known about the reliability of postural sway measures in healthy elderly adults. Moreover, there is no standardized balance test protocols such as an efficient number of repeated measurements for older people. Therefore, we investigated test-retest reliability of center of pressure (COP) variables during static balance performance in elderly adults. Twenty-five elderly adults (15 elderly men and 10 elderly women) were asked to perform quiet standing balance test on a self-developed force platform. COP-based variables, i.e., COP mean distance, sway area, mean velocity, mean frequency, maximum frequency, and maximum power amplitude were derived from the COP data. For the test-retest reliability of each COP-based variable, intraclass correlation coefficient (ICC) was assessed in two-trials and three-trials of balance test. Mean velocity showed the highest ICC values in all directions (ICC = 0.832–0.922). Frequency domain variables presented lower reliability than time domain variables. Additionally, elderly adults did not affect the number of repeated measurements in most postural balance variables. These results suggest that time domain variables are more reliable variables than frequency domain variable and that balance test of two trials might be rather effective for elderly adults. These findings can be used to develop an optimal protocol of static balance test and select postural balance variables for elderly adults.