Mixed Reality as an Environment for Reaction Speed Assessment in Physically Active Young Adults: Measurement Reliability and Participant Experience Compared with Immersive Virtual Reality

Mixed reality (MR) delivered through video see-through headsets could enable reaction-speed assessment while preserving awareness of the physical environment, but its measurement properties remain unclear. This study assessed the reliability of reaction-speed measurements in MR and compared performance and user experience with immersive virtual reality (VR). Forty university students (20 women; age 22.9 ± 2.3 years) completed three 1 min Reaction–Micro Wall trials in each environment in counterbalanced order using Meta Quest 3 and Rezzil Player. Mean reaction speed (RS) and the number of hits per minute (hits/min) were analyzed; enjoyment, flow, and presence were assessed with validated questionnaires. Single-trial intraclass correlation coefficients were good in both environments (0.797–0.884; all p < 0.001) and slightly higher in MR. RS (VR: 517.4 ± 44.6; MR: 521.9 ± 60.3 ms; p = 0.600), hits/min (p = 0.742), and presence (p = 0.577) did not differ significantly. VR elicited greater enjoyment (p = 0.011) and flow (p = 0.003). Cross-environment associations were moderate (RS r = 0.494), and Bland–Altman analysis showed negligible bias (−4.6 ms) but wide limits of agreement (−111.3 to +102.2 ms). MR enables reliable group-level reaction-speed assessment; no significant differences between the environments were detected, although equivalence was not formally tested, and longitudinal monitoring of individuals should be conducted consistently within one environment.