Developing a Novel Augmented Reality-Based Sports Therapy System (STAR): A User-Centered Design Study Focusing on Usability and User Acceptance

Background: Augmented reality (AR)-based systems offer novel opportunities for digital support in physiotherapy and rehabilitation. This is especially relevant in the context of an aging population and the growing shortage of healthcare professionals. Methods: This study employed a user-centered design with iterative prototype refinement and investigated the perceived usability and user acceptance of a prototype AR-based sports therapy system (“STAR”), developed within an ongoing interdisciplinary research project, from the perspectives of patients and healthcare professionals across one iteration cycle. After an initial needs analysis (T0), participants interacted in an observer role with the system at two time points (T1, T2) using an AR headset (Microsoft HoloLens 2). They did not perform exercises but only interacted with the application by navigating through the system and viewing the exercise demonstrations. Between T1 and T2, a tutorial was integrated, exercise animations and voiceovers were revised, and voiceover controls and navigation were optimized. Usability was measured using the System Usability Scale (SUS), and user acceptance via the Technology Usage Inventory (TUI). Results: A total of 15 participants (10 patients and 5 therapists) completed both testing sessions. The average SUS score across both patients and therapists improved from 54.5 (SD = 18.8) to 71.2 (SD = 13.1), reflecting a statistically significant increase in perceived usability (p < 0.001). The usability rating improved from “ok” to “good” according to the SUS interpretation scale. The TUI subscales skepticism, immersion, accessibility and usability improved significantly, while interest, usefulness and intention-to-use only showed trend-level changes. Conclusions: The findings suggest that a user-centered development process can enhance the perceived usability and user acceptance of AR- based virtual care tools during the prototype stage by providing early-stage empirical evidence linking specific user-centered design interventions to changes in Technology Acceptance Model-related acceptance constructs.