Effect of virtual reality environment complexity on tolerance and locomotor performance in healthy subjects

Early and effective rehabilitation is essential to optimize functional recovery and preserve patient autonomy in individuals with motor impairments. Among emerging gait rehabilitation approaches, Virtual Reality (VR) enables the simulation and control of ecologically valid environments and can reproduce complex situations from daily life. However, despite its increasing use for walking, it remains unclear how progressive increase in virtual environment complexity affects locomotor performance. Addressing this gap is essential to improve clinical understanding and ultimately optimize patient rehabilitation and care by understanding the influence of environmental constraints in walking. The aim of this study is to evaluate how increasing the complexity of virtual environments is tolerated by healthy subjects and affects locomotor performance and user immersion. Forty-five healthy volunteers performed flat and slope walking under two real conditions and three immersive VR conditions with increasing complexity. Locomotor parameters were recorded using inertial measurement units. Participants completed tolerance, incarnation and presence questionnaires and performed stability measurements using a baropodometric platform. Tolerance rate was 97.8% and 100%, without falls. No significant differences were observed in the overall questionnaire scores. Walking speed, cadence and stride length decreased significantly in immersions compared with real conditions for flat and sloped walk (p < 0.001). A significant increase in cadence between the virtual laboratory compared to the complex virtual environment was found (+ 2.1 step/min, p = 0.042) during flat walk only. Increasing VR environmental complexity appears to modulate locomotor performance in healthy individuals. Further studies in patient populations are needed to support clinical translation.