Effects of Elevated Height in Virtual Reality on Postural Control in the Semi-Tandem Stance.

Standing at elevated heights can elicit postural adjustments often characterized by reduced center of pressure (COP) magnitude, higher frequencies, and increased irregularity. While often attributed to postural stiffening, such changes may also reflect a shift toward more automatic control. However, most height-related studies use a feet-parallel stance, which may not be generalized to more constrained foot positions like semi-tandem, which are often encountered in real-world height situations. This study investigated the effects of acute virtual height exposure on postural control in a semi-tandem stance. Twenty young adults stood on a force platform under three conditions: (1) no VR, (2) VR sidewalk at ground level, and (3) VR elevated plank. Each participant completed six 60-second trials per condition. Repeated-measures ANOVAs revealed that wearing the VR headset alone affected postural control, with further changes under height exposure. Height was associated with increased COP frequency and irregularity, suggesting more automatic control. However, due to biomechanical constraints, the semi-tandem stance may have influenced postural strategies, resulting in increased COP variability. These findings support the use of VR to study postural threat and highlight the role of foot position in postural adaptations.