Postural control in standing: role of vision and additional support

The purpose of the study was to investigate the availability of vision and additional support on anticipatory (APAs) and compensatory (CPAs) postural adjustments and their interaction. Eight healthy adults were exposed to external perturbations induced at the shoulder level while standing with and without holding onto a walker in full vision and while blindfolded. Electrical activity of the trunk and leg muscles and center of pressure (COPAP) displacements were recorded and quantified within the time intervals typical of APAs and CPAs. The results showed that with full vision, there was no difference in both APAs and CPAs in standing with and without holding onto a walker. With subjects holding onto a walker, CPAs in standing blindfolded were comparable to CPAs in full vision: this was seen in changes in the electrical activity of most of the muscles at the individual muscle, joint, and the muscle group levels as well as in COPAP displacements. The findings suggest that: (1) in conditions where vision is available, vision overrules simultaneously available proprioceptive information from the support, (2) while in conditions where vision is not available, proprioceptive information from the support or support itself could be substituted for vision. It is possible to suggest that using a non stabilizing support could be a valuable strategy to improve postural control when visual information is not available or compromised.