A comparison of vertical force and temporal parameters produced by an in-shoe pressure measuring system and a force platform

Objective. To investigate the ability of Pedar in-shoe system to measure ve rtical force accurately, by comparing it with the Kistler force platform. Design. In vivo experiment in normal subjects. Background It has been suggested Pedar is highly reliable, but absolute acc uracy of the system with regard to force measurement has not been comprehen sively tested. Methods. Sampling at 99 Hz, using five healthy subjects, simultaneous data were collected barefoot, and in three types of shoes (Trainers, Oxfords, Sl ip-on Deck Type). Six variables obtained from the force/time curve from eac h footstep were compared. Results. The temporal data recorded by Pedar correlated well with that obta ined using Kistler, with significant differences only in overall duration o f the step in Deck shoes (P < 0.001) and Oxford shoes (P < 0.01), and peak to peak barefoot (P < 0.01). Pedar recorded a lower first peak force and mi d-peak force in all cases (P < 0.001). However, the magnitude of the 2nd pe ak force recorded by both systems was significantly different only in Train ers (P < 0.05) and Oxford shoes (P < 0.001). The impulse data obtained with Oxford shoes was not significantly different, although barefoot, Trainers and Deck shoes were significantly lower (P < 0.001) for Pedar, Conclusions. In most cases, comparison of data recorded by the two systems provided good evidence for the accuracy and reliability of temporal measure ments and second peak force measurements taken with the Pedar in-shoe syste m.