Visual feedback of the centre of gravity to optimize standing balance

Force platform biofeedback training, whereby concurrent visual feedback of the centre of pressure (COP) is provided, has previously been used for balance training. Since the goal of balance is to maintain control of the centre of gravity (COG), specific feedback of the COG may be more likely than COP feedback to improve overall balance control. The purpose of this study was to compare the effect of concurrent visual feedback of the COP versus COG on postural control during a novel quiet standing task. Thirty-two young healthy adults (20-35 years old) were recruited. Participants were randomly assigned to receive concurrent visual feedback of either the COP or COG while standing on a foam pad. Training occurred over one session (20-30-second trials). Retention and transfer testing (i.e. without concurrent visual feedback) occurred after similar to 24 h. Variability of the COG decreased, variability of COP-COG increased, and sample entropy increased with concurrent visual feedback. With practice, variability of COP, COG and COP-COG decreased whereas sample entropy increased. The decrease in variability of COP-COG was greater for those who received COG feedback than those who received COP feedback. Training effects on COP, COG and COP-COG variability were not retained after 24 h and removal of visual feedback. However, on retention and transfer testing, sample entropy was significantly higher than on baseline testing, indicating more 'automatic' postural control. These results suggest that concurrent visual feedback of neither the COP nor COG is superior for improving quiet standing balance control. (C) 2014 Elsevier B.V. All rights reserved.