Background and objective: Reduced heart rate variability (HRV) is an indicatorof a malfunctioning autonomic nervous system. Resonant frequencybreathing is a potential non-invasive means of intervention for improvingthe balance of the autonomic nervous system and increasing HRV. However,such breathing exercises are regarded as boring and monotonous tasks.The use of gaming elements (gamification) or a full gaming experience is awell-recognised method for achieving higher motivation and engagement invarious tasks. However, there is limited documented knowledge on how todesign a game for breathing exercises. In particular, the influence of additionalinteractive elements on the main course of training has not yet beenexplored. In this study, we evaluated the satisfaction levels achieved usingdifferent game elements and how disruptive they were to the main task, i.e.,paced breathing training.

Methods: An Android flight game was developed with three game modes thatdiffer in the degrees of multitasking they require. Design, development and evaluation were conducted using a user-centred approach, including contextanalysis, the design of game principle mock-ups, the selection of game principlesthrough a survey, the design of the game mechanics and GUI mock-up,icon testing and the performance of a summative study through user questionnairesand interviews. A summative evaluation of the developed gamewas performed with 11 healthy participants (ages 40-67) in a controlled setting.Results: The results confirm the potential of video games for motivatingplayers to engage in HRV biofeedback training. The highest training performanceon the first try was achieved through pure visualisation rather thanin a multitasking mode. Players had higher motivation to play the morechallenging game and were more interested in long-term engagement.Conclusion: A framework for gamified HRV biofeedback research is presented.It has been shown that multitasking has considerable influence onHRV biofeedback and should be used with an adaptive challenge level.