Can a Visual Biofeedback system based on predictive information improve postural performance?

The aim of this study is to assess if predictive information can be used to implement visual biofeedback (VBF) systems to improve postural performance. The Centre of Pressure (CoP) coordinates, extracted directly from a force plate, are used to implement two different realtime VBF, which respectively use current CoP coordinates (VBFreal_time) and predictive stability information (VBFpredictive). Predictive coordinates are calculated in agreement with time-to collision theory, using the real-time CoP components. In both VBF, subjects know if they are or are not in the stability area by an emoticon image displayed on the computer monitor. The expression of emoticon was smiling if the CoP coordinates were inside the area of stability, it was sad if the CoP coordinates exceed the stability area. Two groups of eighteen healthy young subjects performed the protocol in two different sequences: noVBF-VBFreal_time and noVBF-VBFpredictive. Each condition was repeated three times, and its effect was studied by four parameters extracted directly from CoP coordinates (sway path, sway area, mean amplitude and mean frequency). Both VBFs determine a modification of postural parameters compared to the baseline condition (noVBF) with decrease of sway area and mean amplitude and increase of mean frequency. The comparison between the two VBFs shows significant difference for all parameters except for mean frequency. In particular, sway path, sway area and mean amplitude values for the VBFpredictive decreased more than the same values for the VBFreal_time. The preliminary results may prove useful for the possibility of using this kind of VBF as a tool to improve postural performance.