Characterization of postural stability in a simulated environment of an earthquake using in-shoe plantar pressure measurement

An abled individual is believed to be capable of withstanding and overcoming the severe tremors of an earthquake as has been ascertained in a previous study. However, the event-related physiological mechanisms of human postural stability during an earthquake are subject to further investigation. Accordingly, the objective of this study is to further characterize postural stability in a simulated environment of an earthquake using a pedar-x (novel gmbh, Munich, Germany) in-shoe dynamic plantar pressure measurement system. A foot mask, dividing each of the insoles into seven plantar loading regions, was employed in this study. This paper reports preliminary results obtained from a normal adult female test subject with right side dominance and a normal foot arch. The test trial was comprised of 12 stages, ranging from quiet standing to simulated earthquake magnitude of 6.7 degrees on the Richter's scale, which is considered to be violent. The study metrics included: mean plantar pressure, foot-to-ground contact duration, insole loading area, and the position, displacement, and instantaneous velocity of the center of pressure. The study showed bilateral quantifiable changes in these metrics by foot-mask-region as a result of increasing magnitudes of simulated tremors. The subject was able to defy the overwhelming perturbations and maintain her balance and postural stability throughout the test period. The significance of this study lies in its ability to determine the threshold of falling within different subject populations in the event of an earthquake.