[Is indirect posturography using force plates equivalent to direct posturography by movement analysis? A physical observation]

Piezoelectric force plates are accurate and convenient aids for the monitoring of coordination in erect humans. However, the results obtained with such "indirect" posturographic measurements should not be "over-interpreted". The information on the spatial location of the centre of pressure (CoP) provided by the force plate permits conclusions to be drawn about the regulation of the "sway" of the centre of gravity (CoG) only when other information on the acceleration situation of the body is available. Otherwise the systematic error of the measurement exceeds the amount of the true "sway" even for physiological cyclic movement frequencies of 0.5 Hz or more.