Noisy galvanic vestibular stimulation effect on center of pressure sway during one-legged standing

Noisy galvanic vestibular stimulation (nGVS) involves the application of a weak, noisy, electrical current to the vestibular end organs and their afferent nerves, through electrodes placed bilaterally over the mastoid process. Center of pressure (COP) sway was shown to decrease during nGVS under conditions of static standing posture. However, whether nGVS can improve balance functions other than the static standing posture remains unclear. This study aimed to elucidate the effects of nGVS on COP sway during one-legged standing. We randomly assigned 36 participants to either a control group (sham stimulation), a 0.2 mA group (nGVS at 0.2 mA), or a 0.4 mA group (nGVS at 0.4 mA). All participants were measured for COP sway standing on one leg, with open eyes, both before and during stimulation. In the 0.2 mA group, the sway path length, mediolateral mean velocity, and anteroposterior mean velocity decreased during stimulation compared with before stimulation. Conversely, no significant differences in COP sway were detected for either the control group or the 0.4 mA group. The stimulation effects for all COP sway parameters were significantly higher in the 0.2 mA group than in either the control group or the 0.4 mA group. The results of this study suggested that nGVS not only decreases COP sway during static standing postures but can also reduce COP sway during one-legged standing.