In earlier studies of postural control system, electrical stimulation had been almost used as a disturbance to vestibular system. In this study, to consider whether an electrical stimulation method can be used as a support system for postural maintenance of human quiet standing, we developed the interferential current (IFC) stimulation device. We examined effects of IFC stimulation on center of pressure (COP) trajectory during one leg quiet standing with opened-eyes in the following conditions: 1) without stimulation, 2, 3, 4) IFC stimulations with 40, 60, 80% sensation threshold intensities. We calculated four parameters relative to postural sway, which were corresponded to a variance of COP sway in mediolateral (ML) and anteroposterior (AP) directions (ML SD and AP SD) as “sway degree” in each direction, an area of 95% confidence ellipse for COP distribution as “swept area” and a COP trajectory path length in unit time as “average velocity”. As a result, ML SD and swept area were significantly decreased during the applied IFC stimulation at 80% sensation threshold intensity. On the other hand, AP SD and average velocity were not changed by IFC stimulation. These results suggest that IFC stimulation at sensation-subthreshold intensity may enhance a sensitivity of position sensing of knee joint. We confirmed that IFC stimulation at sensation-subthreshold intensity was effective support method for postural maintenance, especially postural sway in ML direction, during one leg quiet standing in healthy young adults using our prototype IFC stimulation device.

DESCENTE SPORTS SCIENCE Vol.29/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE