A comparison of accelerometry and center of pressure measures during computerized dynamic posturography: a measure of balance

Abstract

Accelerometry (ACC) shows promise as an easily implemented clinical measure of balance. The purpose of the study was to estimate test-retest reliability of ACC measures and determine the relationship between ACC measured at the pelvis and underfoot center of pressure (COP) measures during sensory organization test (SOT) conditions. Eighty-one subjects were recruited from the community with no known orthopedic or vestibular deficits (19-85 years). Subjects completed three consecutive, ninety second trials for each of the six SOT conditions, while wearing the accelerometer. ACC and COP time series were described by calculating the normalized path length, root mean square (RMS), and peak-to-peak values. The test-retest reliability of the three measures within each SOT condition was estimated over three trials using the intraclass correlation coefficient. ACC and COP test-retest reliability were similar, ranging from 0.63 to 0.80 using ACC and 0.42 to 0.81 using COP for the measure of normalized path length. Linear regression between ACC and COP measures showed significant correlation under almost every SOT condition using both single and average measures across trials. The degree of association between COP and ACC was equivalent when using the first trial or the 3-trial average, suggesting that one trial may be sufficient. The use of accelerometry may have value in estimating balance function and minimizing clinical evaluation time.

Copyright © 2011 Elsevier B.V. All rights reserved.

Figures

Fig. 1

(A) Close up view of the accelerometer system; (B) anterior view of accelerometer system worn by subjects; (C) schematic of accelerometer system (brown belt) worn by subject on EquiTest® machine with harness (blue). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 2

Center of pressure and pelvic acceleration (mean, S.D.) by test condition for (A) COP normalized path length, (B) ACC normalized path length, (C) COP RMS, (D) ACC RMS, (E) COP peak-to-peak, and (C) ACC peak-to-peak: bars represent group mean of three-trial averages for each SOT condition.