The purpose of this study was to investigate the day-to-day reliability of evaluation parameters for the body center of pressure (BCP). The subjects were healthy young adults: 12 males and 18 females. The measurement of BCP for 1 minute was carried out 3 times with a 1 minute rest for each subject. This measurement was repeated on five consecutive days at the same time. The measurement device used was Anima's stabilometer G5500. The data were recorded every 20 milliseconds. Sixty evaluation parameters with higher trial-to-trial reliability were selected from the following domains: distance, center of pressure, distribution of amplitude, area, velocity, power spectrum, and vector for body sway.
The 95% confidence intervals of the limits of agreement for repeated measurements and the coefficient of variance were ±0.008-2.018, 21.18-51, 42, respectively. The 95% confidence intervals for all parameters were not significant. The variance coefficients of mean distance, standard deviation of velocity of x and y-axis, slope by the cumulative frequency of y-axis on the distribution of amplitude, velocity, and power spectrum were relatively small. The intraclass correlation coefficients (ICC) were over 0.7 for almost all parameters. There was a significant difference among the trials during the five days in some parameters.
Based on the present results, the following parameters were considered to be effective to evaluate BCP because they had a higher reliability: mean distance, area, amplitude, velocity, and power spectrum for velocity of body sway of x and y-axis, and vector for velocity of body sway.
