Understanding Heart Rate Controllability for High-Intensity Interval Training (HIIT) Gaming: A Mixed Method Study

This is the authors' abstract. We don't add key points for this paper.

Heart rate (HR) controllability—the ability to intentionally regulate HR—is central to high-intensity interval training (HIIT), where the efficacy depends on keeping HR within targeted intensity zones. While interactive HIIT games are known to enhance exercise performance, how game narrative and interface elements affect dynamic HR control remains underexplored. To investigate this, we developed an interactive biofeedback system that uses real-time HR as both feedback and a primary control input. We conducted a two-stage within-subject study (N = 14) comparing a game-based condition (Experiment 1) with a simplified interface (Experiment 2), combining physiological measures with thematic analysis. Results indicated that game elements improved target-zone adherence in high-intensity sessions, whereas the simplified interface yielded higher adherence in moderate-intensity sessions. Qualitative findings showed that narrative elements provided strong initial motivation but occasionally induced psychological stress that hindered HR descent. These findings suggest intensity-dependent biofeedback scaffolding and adaptive narrative interventions for personalized digital health platforms.