Efficacy of TtB-Based Visual Biofeedback in Upright Stance Trials

Several studies have shown the effect of visual biofeedback (VBF) on postural control with real-time presentation of centre of pressure (CoP). However, up to now no study has yet focussed on the effect that a predictive VBF could have on postural control. The aim of this study is thus to determine whether the Time-to-Boundary function (TtB) could be used as an efficacious VBF in static posturography.

The CoP coordinates were extracted from force plate data and elaborated to calculate TtB in real-time.

Two groups of six healthy young subjects executed the protocol in two different sequences composed of the following conditions: noVBF-VBF1 (real-time presentation of CoP) and noVBF-VBF2 (real-time TtB presentation). Each condition was repeated three times.

The effect of the two VBFs was studied by five parameters extracted directly from CoP coordinates (sway area, sway path, mean amplitude, frequency bandwidth that contains 95% of the power spectral density of antero-posterior and medio-lateral displacement) and two parameters by fraction Brownian motion model (exponential radial terms Hrs and Hrl corresponding to the short-term and long-term region Hurst exponents).

The comparison between the VBF conditions didn’t show significant differences in the studied parameters. This evidence suggests that the participants react in similar way in both conditions, and it opens the possibility of using a predictive VBF as a tool to facilitate postural control in upright stance.