Evaluating therapist representation techniques in mixed reality-based tele-rehabilitation exergames

Recent advancements in technology have improved rehabilitation through tele-rehabilitation, offering flexible and personalized care with remote monitoring. Interactive ``exergames'' using eXtended Reality (XR) enhance treatment by combining traditional methods with digital gaming. However, there is limited research on virtual therapist representations. This study evaluates three techniques for therapist representation in Mixed Reality (MR) tele-rehabilitation: audio-only, video, and 3D avatar. Using a collaborative exergame for upper limb rehabilitation in Multiple Sclerosis (MS) patients, the study assesses these methods based on peer acceptance, user experience, social and co-presence, and naturalness, aiming to optimize therapist representation in MR-enabled tele-rehabilitation contexts.