This study aimed to explore the feasibility and effectiveness of immersive Virtual Reality (VR) as an alternative to traditional High-Intensity Interval Training (HIIT) by comparing physiological and psychological outcomes in physically active university students. The pilot randomised controlled trial utilised a parallel design involving two groups: one group performed HIIT using the Facebook Oculus Quest 2 VR headset with the "FitXR" fitness game, while the other undertook traditional HIIT training that mirrored the movements and actions of the VR game.

The study's findings suggest that fully immersive VR provides a unique and potentially more enjoyable alternative to traditional HIIT, particularly because it may enhance motivation while still achieving health benefits. This pilot research study highlights VR's potential to reach high-flow states in exercise, where individuals become deeply absorbed and derive satisfaction from the activity. It also lays the groundwork for future studies involving larger sample sizes and clinical populations to further investigate the psychological and physiological impacts of VR-based exercise.

In summary, this pilot randomised controlled trial found that immersive VR could be a feasible and effective alternative to traditional HIIT training, offering similar physiological benefits while enhancing exercise motivation and enjoyment. Further research is necessary to validate these preliminary results and extend them to diverse populations.

Study Objectives and Design This study was designed as a pilot randomised controlled trial (RCT) to investigate the feasibility, efficacy, and effects of immersive VR compared to traditional HIIT on physiological and psychological outcomes in physically active university students. The parallel-design trial was conducted in accordance with the CONSORT guidelines and approved by the Teesside University Health Research Ethics Sub-Committee. The VR intervention used the Facebook Oculus Quest 2 VR headset with the fitness game "FitXR," while the non-VR group completed traditional HIIT that replicated the same movements as in the VR game.

Participants and Recruitment A purposive sampling method was used to recruit ten healthy physiotherapy students from Teesside University. Participants had to lead an active lifestyle, defined as performing either 150 minutes of moderate exercise weekly or 75 minutes of vigorous-intensity aerobic exercise, and have no prior experience with VR-based exercise. Those with medical conditions preventing them from exercising or those unable to give informed consent were excluded. Participants were recruited via email through a gatekeeper, indicating their willingness to participate by contacting the research physiotherapist directly. The allocation to either the VR or non-VR group was stratified by gender and block-randomised in blocks of five using a computer-generated software (Research Randomizer).

Interventions

Exergaming via VR:

Participants in the VR group used the Facebook Oculus Quest 2 and "FitXR," a fitness game in high-speed HIIT class mode. The 15-minute session included functional movements such as squats, lunges, and trunk rotations while trying to hit virtual targets by punching. The training session had a 10-second rest between each interval, and participants followed instructions from a virtual trainer.

Traditional HIIT:

The non-VR group followed a traditional HIIT session that mirrored the movements from the "FitXR" game. Participants replicated movements such as squats with punches, as pre-recorded and displayed on a laptop. The session matched the VR group's overall duration and intervals.

Safety and Blinding To ensure safety while using the VR headset, participants were restricted to a 3m by 3m safety boundary. Stepping out of the boundary automatically paused the game, activating external cameras to provide real-world visibility. Blinding was not feasible due to the nature of the intervention, but the researcher responsible for the data analysis was unaware of the group allocations to reduce bias.

Outcome Measures

Physiological Outcomes:

Heart Rate: Measured using a Polar RS400 monitor. Exercise intensity was calculated as a percentage of the maximum heart rate (%HRmax) and heart rate reserve (%HRR). The intensity was categorised according to American Heart Association standards.

Rating of Perceived Exertion (RPE): Measured using Borg's CR-10 scale every five minutes. Scores ranged from 0 (rest) to 10 (maximum effort).

Psychological Outcomes:

Flow State Scale (FSS): Assessed engagement and motivation using a 36-item questionnaire with nine subscales. Participants rated items on a 5-point Likert scale from 1 (strongly disagree) to 5 (strongly agree). The subscales measured challenge-skill balance, action-awareness merging, clear goals, unambiguous feedback, and other factors.

Statistical Analysis A frequentist approach was employed with SPSS software (version 26). Independent-samples t-tests were used with a significance level of 0.05, and effect sizes were expressed using Cohen's d (small = 0.2, moderate = 0.5, large = 0.8). Bayesian data analysis was conducted with JASP software to assess the robustness of findings. Bayes factors were calculated to compare evidence for alternative versus null hypotheses. Robustness checks were performed to ensure results remained consistent across different prior distributions.

Sample Size and Feasibility Given that this was a pilot study, the emphasis was placed on assessing feasibility rather than ensuring the study was fully powered. As such, recruitment spanned a period of time with the objective of enrolling as many patients as possible, without specifying a target participant number to achieve optimal study power. An aim of this study was, therefore, to explore feasibility and preliminary outcomes, which will inform future, larger-scale research

Conclusion This pilot study provides preliminary evidence that immersive VR training can offer a feasible alternative to traditional HIIT, achieving comparable physiological benefits with potentially greater intrinsic motivation and engagement. Future studies with larger sample sizes are needed to validate these findings and assess VR's impacts on diverse clinical populations.

Inclusion Criteria:

1. Teesside University physiotherapy student.
2. Participants willing and able to give informed consent.
3. Have an active lifestyle (performing either 150 minutes of moderate exercise weekly or 75 minutes of vigorous intensity aerobic exercise).
4. No prior experience with exercise using the VR headset.

Exclusion Criteria:

1. Have a known medical condition that would prevent them from exercising.
2. Are not able to provide informed consent.

The researcher who completed the data analysis (JR) was blinded to the participants and specifics of the intervention.