Age-related effect of visual biofeedback on human balance control

Real-time visual biofeedback (VBF) is a voluntary control mechanism of postural activity using additional visual information of the centre of pressure (CoP) position. The aim of the study was to examine balance control performance in subjects of different age during the stance on different support surfaces with and without VBF. The study was performed on 20 young and 13 older subjects during stance on firm and foam surface in the conditions with and without VBF. Body sway was measured by force platform (CoP) and by two accelerometers located on the upper (Th4) and lower trunk (L5). Additional VBF showed the improvement of body balance with decreased CoP parameters RMS (root mean square), Ax (amplitude of postural sway in left-right direction) and Ay (amplitude of postural sway in forward-backward direction) in both age groups, but not with the same extent. Elderly subjects were able to improve their balance only during the stance on foam surface. Trunk tilts recorded by accelerometer at L5 level showed reduction of measured parameters only in the group of young subjects. Body tilts recorded by accelerometer placed at Th4 level showed no reduction of parameters. The present results confirm knowledge about the stabilizing effect of additional VBF in stance control. Young subjects are able to improve their balance using additional VBF during the stance on both types of support surface more effectively than elderly subjects. However, the extent in which VBF of the CoP position can reduce postural sway is limited mainly on CoP displacements.