## 4 Discussion
This system is designed to be more inclusive and user-friendly, particularly for patients with physical, cognitive, and/or emotional constraints [67]. By removing the barrier often presented by individual headsets, the CAVE-based system allows for broader accessibility and more effective engagement with the intervention. In addition, delivering the intervention in a group-based format offers significant advantages over individual IVR sessions. Group-based IVR interventions foster social interaction, enhance motivation, and encourage constructive feedback among participants, all of which are key elements in promoting successful rehabilitation outcomes [68]. Engaging in shared virtual experiences allows participants to support one another, exchange insights, and collectively navigate the challenges of the rehabilitation process. Moreover, the presence of peers in a virtual group setting can serve as a strong motivational driver, reinforcing accountability and adherence to the intervention. Witnessing the progress of fellow participants can inspire individuals to stay engaged and committed. Lastly, and from a practical standpoint, group-based IVR interventions also offer significant advantages in healthcare settings with high patient volumes, such as those managing PCC rehabilitation. The scalability of group-based interventions presents a potentially efficient way to deliver advanced therapeutic technologies in a cost-effective and resource-efficient manner [69]. In summary, by integrating the benefits of social interaction, enhanced motivation, improved performance, and increased scalability, group-based IVR interventions represent an innovative and resource-efficient approach to rehabilitation. Despite the promising results presented, several limitations of this study should be acknowledged. First, the small sample size of 18 participants, with only nine individuals in each group, limited the statistical power of our findings and restricted the ability to generalize the results obtained. Larger-scale studies are needed to confirm the findings presented here and to explore whether similar outcomes could be achieved in a more diverse population. Additionally, the absence of a control group that did not receive the intervention, or which received standard care, made it difficult to isolate the impact of the multimodal IVR intervention on HRV. Similarly, the multimodal nature of the intervention, which combined cognitive training, physical exercise, and mindfulness, made it challenging to discern which specific components contributed to the changes in HRV that were observed. Future studies, with larger samples, may address this challenge by using a factorial design to isolate the effects of cognitive training, physical exercise, and mindfulness on HRV. For instance, separate experimental groups could help determine individual and combined contributions of the IRV multimodal training. Furthermore, HRV measurements were taken at only three points in time: after the first session, at mid-intervention, and after the final session. More frequent HRV assessments, conducted throughout the intervention, would provide a clearer picture of how HRV changes over time and how participants respond at different stages of the intervention. Finally, the lack of follow-up HRV measurements after concluding the intervention left it unclear as to whether the observed changes in HRV were sustained over time. Future studies should take a longitudinal approach, which could provide insights into the sustained HRV changes of the intervention. In conclusion, this study provides additional insights about how controlling HRV parameters within IVR interventions offers promising tools for monitoring both the physiological and psychological recovery of PCC patients. Our primary hypothesis of observing significant improvements in HRV over the course of the intervention was not confirmed, as we observed reductions in HRV during the early stages of the intervention.