## 4 Discussion  
This study found that trunk stabilization education provided prior to VR-based training led to significantly greater improvements in postural control, dynamic balance, and sway distance compared to VR training alone. Specifically, the experimental group showed larger gains in K-TIS, PASS, BBS, and LOS scores as well as significant reductions in sway distance under both visual conditions. These results suggest that preparatory trunk stabilization may enhance the effectiveness of VR-based balance rehabilitation by promoting core activation and improving postural symmetry. Postural control, which forms the foundation for basic activities of daily living in early stroke rehabilitation, involves responding to unexpected perturbations and controlling body movement during voluntary shifts of the center of mass [6; 36]. In this study, postural control was assessed using the K-TIS and PASS, both of which are reliable and clinically relevant measures in stroke rehabilitation. The experimental group demonstrated significantly greater improvement in PASS scores compared to the control group. This finding is consistent with previous studies reporting that trunk stabilization education improves selective motor control and reduces trunk muscle imbalance [7; 19]. K-TIS scores also significantly improved in both groups, suggesting a general effect of task-based training. However, the experimental group achieved a significantly greater change, supporting the added benefit of pre-training trunk stabilization in facilitating trunk  
Figure 5: Pre- and post-treatment comparisons of static balance (eyes-closed) measures between groups. control through co-contraction of core muscles such as the abdominals and multifidus [17]. Even in the control group, which received only VR-based training, significant improvements in K-TIS scores were observed (\(p<0.05\)), suggesting that repetitive task-based VR training can also promote trunk function through motor learning. Although both the Postural Assessment Scale for Stroke (PASS) and the Berg Balance Scale (BBS) include elements related to postural transitions, these tools assess distinct but complementary aspects of balance control. The PASS, as described by [PERSON] et al. [30], primarily focuses on the ability to maintain and change posture in early-stage stroke rehabilitation, particularly capturing static postural control and transitions. In contrast, the Berg Balance Scale (BBS) focuses on dynamic balance and functional mobility by assessing tasks that challenge the center of mass during movement [35]. Accordingly, the two scales were analyzed separately in this study to reflect the multifaceted nature of postural control and dynamic balance in stroke patients. Dynamic balance, the ability to voluntarily adjust posture or COP in response to disturbances, was assessed using the BBS and LOS [5]. The BBS, widely used to estimate rehabilitation outcomes and fall risk, evaluates static and dynamic balance through 14 functional tasks [34]. Trunk stabilization exercises have been shown to improve postural control and dynamic balance in patients with subacute stroke [7; 37]. Consistent with this, the experimental group showed significant improvements in BBS scores, suggesting that pre-training trunk stabilization enhances neuromuscular coordination and dynamic balance. The BBS is also sensitive in detecting dynamic balance impairments and correlates closely with mobility and gait performance [36]. The LOS was assessed using the BioRescue, which measures the maximum COP displacement during voluntary weight shifting. Improvements in the LOS following weight-bearing training using pressure biofeedback have been reported [38; 39; 25]. In this study, both groups showed significant improvements in the LOS, with the experimental group demonstrating significantly greater changes in voluntary weight shifting, suggesting enhanced voluntary weight shifting and postural control, particularly for patients with hemiplegia.