To Stand or to Sit? Examining the Influence of Player Posture on Balance Alterations Associated to Immersive Virtual Reality Exposure

Due to reduced cost and improved performance, immersive Virtual Reality (VR) is spreading in different fields such as education, industry, and rehabilitation. However, while considered promising for improving health and well-being, there is evidence regarding the possibility to originate adverse effects in terms of motion sickness symptoms, which can be objectively assessed by means of balance alterations. Among other factors that influence this phenomenon (i.e., exposure time, optical flow, hardware type, etc.) player's posture is particularly important especially in the case of immersive VR administration for training or rehabilitation purposes in special populations. However, empirical data on how user's posture is associated to cybersickness during immersive VR experiences are limited. To this aim, we investigated the impact of seated and standing postures on postural control, measured by postural sway, in response to immersive VR. Seventy-six healthy participants underwent pre- and post-VR assessments following a 10-minute simulated rollercoaster experience. Results revealed that postural control is differently affected by standing or sitting position only when sway analysis is performed in absence of visual cues. Both sway area and Center-of-Pressure (COP) path length significantly decreased for the sitting group, while no changes were observed for the standing position. These differences highlight the primary role of visual input in postural performance and elucidates distinct effects of VR player's posture on the postural control system. Standing during VR exposure posed challenges to balance maintenance due to conflicting sensory inputs, leading to temporary and slight increases in postural sway. Conversely, seated posture was characterized by decreased engagement of lower limbs, facilitating enhanced postural stability post-VR session, possibly due to VR training effect. Our study emphasizes the importance of considering user's posture in VR interventions, suggesting for customized approaches in therapeutic and training settings. Clinicians should carefully consider patients' postures during VR interventions to improve outcomes and safety.