## 4 Discussion
Our findings showed no statistically significant differences in HRV outcomes between the reduced and extended session groups; this suggested that simply increasing the number of sessions did not offer any additional HRV benefits. It is possible that factors such as the intensity and content of the sessions could play a greater role in influencing HRV than the total number of sessions. In line with this hypothesis, previous research has demonstrated that intensity of exercise has a more pronounced effect on HRV than session duration or frequency [61]. For example, a previous study reported that HRV decreased with the intensity of exercise, with the resulting reductions in HRV being more substantial than those solely associated with the number of sessions [62]. While no significant improvements in HRV metrics were observed during the intervention, this study offers a novel approach for assessing HRV in a group of patients with PCC following an IVR rehabilitation program. A key innovation was the use of the Electrocardiogram Weight Scale [47; 48] for HRV measurement, which meets important healthcare criteria. The device is wearable, comfortable, and non-intrusive, making it ideal for patient compliance in rehabilitation, and more specifically for PCC. It is adaptable, with various settings, portable, and can be easily attached to a wheelchair, providing flexibility for different patient needs. Additionally, it is cost-effective, which enhances the potential for its widespread use. The wireless communication feature streamlines data collection and improves usability by eliminating the need for cables, thereby allowing real-time monitoring while ensuring patient mobility and comfort during sessions. One of the objectives of this study was to minimize the preparation and measurement time required to obtain HRV data. Reducing these times could mitigate the impact of waiting periods between measurement and the start or end of rehabilitation, thereby providing more accurate estimates related to the rehabilitation process. Additionally, shorter measurement times would facilitate integration into existing medical routines. While many portable ECG-based solutions offer this capability, the use of the scale presents two key advantages. Firstly, users are already accustomed to minimizing movement on the scale due to routine weight measurements. As a result, this platform has demonstrated a reduced influence of motion artifacts, even without direct medical supervision. Secondly, beyond ECG signal acquisition, the platform can simultaneously capture additional signals, such as impedance plethysmography, which provides insights into respiratory rhythm. Although this aspect was not the primary focus of the study, it holds significant potential for future research. Numerous studies have associated PCC with cardiovascular deterioration, suggesting that this platform could be valuable for monitoring patients outside of a hospital setting. Secondly, this study presents a number of multimodal IVR interventions, which may combine cognitive, physical, and emotional elements. It has also been shown to offer a cost-effective and efficient way to enhance traditional rehabilitation approaches for individuals with PCC [40; 41; 42; 63; 64]. IVR systems offer immersive environments that engage patients in ways that traditional rehabilitation techniques may not, making them a promising tool for improving the cognitive and psychological well-being of vulnerable populations [65]. However, despite the potential benefits of IVR, current systems often rely on individual headsets, which may be unsuitable or inaccessible for certain populations due to their technological, physical, and/or cognitive limitations [66]. Our study addresses this challenge by employing a novel IVR setup: a CAVE-based MK360 IVR system, which eliminates the need for individual headsets and creates an immersive, room-scaled, multisensory environment.