Detection of hesitant dynamic postural control

Abstract

Postural balance is often studied in order to understand the effect of sensory degradation with age. The aim of this study is to identify a hesitant step-up pattern that could be linked to an increasing risk of falling in the elderly. The methods used are autoregressive moving average (ARMA) (rate of changes or fluctuation) and the area of a curve under the slope of the Z-force signal (Z-Area) during stepping up. Dynamic balance is evaluated using a force plate for 10 control subjects, 10 elderly subjects and 10 rest home subjects under control (eyes open) conditions. Each subject is tested once per weekday for three weeks. Temporal and ground reaction force parameters are measured. Lower values of ARMA variance or rate of changes, and a higher value of Z-Area are indicative of a more hesitant step up. Control subjects have significantly higher values of ARMA than the rest-home dwelling elderly, thus providing a sensitive method for identifying the subtle changes in z-force signals associated with a hesitant step-up. Similarly, elderly subjects have significantly greater Z-Area values than the control subjects. The ARMA and Z-Area parameters enable the detection of a hesitant step-up that could be related to an increasing risk of falling.