Idiosyncratic characteristics of postural sway in normal and perturbed standing

Dataset from study "Idiosyncratic characteristics of postural sway in normal and perturbed standing", performed at the University of Birmingham. <br><br>The RMS of body angular velocity is a reliable and much used measure of spontaneous sway. It reflects the small, apparently random, adjustments in torque required to stabilise the standing body. Some individuals sway more than others. Are such people particularly unstable when standing on a moving surface? The propensity of individuals to tilt when their supporting surface is slowly inclined has been less studied. This measure reflects body orientation, i.e. regulation of body position with respect to the gravitational vertical when the standing surface is tilted. In this study, we assess individual postural sway size and tilt when subtle continuous sinusoidal disturbance is applied to the standing platform. We found no correlation between measurements, suggesting that the short-term regulation of stability and the longer-term regulation of orientation are controlled by different processes. However, the consistency of each measurement was fair to excellent between conditions. The consistency between conditions of two distinct unrelated measurements of postural sway size reflects its idiosyncratic characteristic. Our results suggest that more exaggerated responses to a tilting standing surface may better predict individuals who are at particular risk of falling. However, these individuals will not necessarily have particularly large spontaneous sway.