Visual feedback and guided balance training in an immersive virtual reality environment for lower extremity rehabilitation

Balance training is essential for physical rehabilitation procedures, as it can improve functional mobility and enhance cognitive coordination. However, conventional balance training methods may have limitations in terms of motivation, real-time objective feedback, and personalization, which a virtual reality (VR) setup may provide a better alternative. In this work, we present an immersive VR training environment for lower extremity balance rehabilitation with real-time guidance and feedback. The VR training environment immerses the user in a 3D ice rink model where a virtual coach (agent) leads them through a series of balance poses, and the user controls a trainee avatar with their own movements. We developed two coaching styles: positive -reinforcement and autonomous -supportive, and two viewpoints of the trainee avatar: first -person and third -person. The proposed environment was evaluated in a user study with healthy, non -clinical participants (n = 16, 24.4 +/- 5.7 years old, 9 females). Our results show that participants showed stronger performance in the positive -reinforcement style compared to the autonomous -supportive style. Additionally, in the thirdperson viewpoint, the participants exhibited more stability in the positive -reinforcement style compared to the autonomous -supportive style. For viewpoint, participants exhibited stronger performance in the first -person viewpoint compared to third -person in the autonomous -supportive style, while they were comparable in the positive -reinforcement style. We observed no significant effects on the foot height and number of mistakes. Furthermore, we report the analysis of user performance with balance training poses and subjective measures based on questionnaires to assess the user experience, usability, and task load. The proposed VR balance training could offer an interactive, adaptive, and engaging environment and open new potential research directions for lower extremity rehabilitation.