Selection of useful parameters to evaluate center-of-foot pressure movement.

This study aimed to objectively summarize the parameters for evaluating the center-of-foot pressure and to select useful parameters with high reliability and validity with 220 healthy university students. In addition, 50 healthy university students were selected to examine cross validity. The measurement of center-of-foot pressure was carried out 3 times with a 1-min. rest and the mean of Trials 2 and 3 was used for the analysis. The data sampling frequency was 20 Hz. 34 parameters were selected from 6 domains: distance, distribution, area, velocity, spectrum, and vector. As a result of factor analysis the following four factors were interpreted: unit time sway, front-back sway, left-right sway and high frequency band sway. Their intraclass correlation coefficients were very high (ICC=.89-.95). Five parameters representing each factor were selected using stepwise selection by regression analysis. There were no significant differences between the mean factor scores estimated by the above five parameters in the original and in cross-validity groups, and relationships between factors in both groups were very high. The center-of-foot pressure may be predicted and systematically evaluated by the above four factors. Five parameters selected from each factor are considered to be useful ones with high validity and practicability.