Reliability of an in-shoe pressure measurement system during treadmill walking

We examined the reliability of in-shoe foot pressure measurement using the Pedar in-shoe pressure measurement system for 25 participants walking at treadmill speeds of 0.89, 1.12, and 1.34 meters/sec. The measurement system uses EMED insoles, which consist of 99 capacitive sensors, sampled at 50 Hz. Data were collected for 20 seconds at two separate times while participants walked at each gait speed. Differences in some of the loading variables across speed relative to the total foot and across the different anatomical regions were detected. Different anatomical regions of the foot were loaded differently with variations in walking speed. The results indicated the need to control speed when evaluating loading parameters using in-shoe pressure measurement techniques. Coefficients of reliability were calculated. Variables such as peak force for the total foot required two steps to achieve a coefficient of reliability of 0.98. To achieve excellent reliability (> 0.90) in the peak force, force time integral, peak pressure, and pressure time integral across the total foot and the seven regions, a maximum of eight steps was needed. In general, timing variables, such as the instant of peak force and the instant of peak pressure, tended to be the least reliable measures.