## 4 Discussion
These improvements on dynamic balance could play a significant role in preventing ankle injuries, further emphasizing the value of the improvements achieved with the exercise intervention using the specific instability device. Balance training on unstable devices is a cost-effective, accessible, and efficient method for improving dynamic balance. An interesting aspect of this program is the use of an innovative, configurable instability device, which differs from conventional instability devices by specifically targeting the foot and ankle. This ankle-specific approach minimizes the need for additional attention to other body regions, potentially making it an efficient tool for improving balance. Additionally, the results suggest that the inclusion of tDCS may not provide sufficient additional benefits to justify its use in healthy, recreationally active individuals, given the minimal improvements observed in the BB + tDCS group and the logistical and equipment demands associated with its application. However, this finding is a valuable insight into the use of tDCS in the context of motor learning in healthy subjects, which can help clinicians refine their practice (e.g., by avoiding the allocation of resources to an apparently ineffective intervention). Despite its contributions, this study is not without limitations. The small sample size may limit the generalizability of the findings, and the relatively short intervention duration may not reflect the potential long-term benefits of tDCS. In addition, while improvements were observed in the CS of the YBT, the reference values reported in the literature were not fully achieved. This could be due to the intervention's duration or intensity, or to the notably low baseline performance of both groups. However, as previously discussed and to the best of our knowledge, no reference values have been specifically established for a young, physically active population not engaged in a particular sport. Therefore, it would be misleading to assume that our studied population is failing to meet a certain threshold and thus at a higher risk of lower limb injuries based solely on comparisons with other populations. Lastly, the tDCS protocol selected for this study may not have been the optimal choice for combination with a balance training program on a selective instability device in healthy individuals. Nevertheless, given the lack of prior research in this area, we encourage future studies to refine the duration and intensity of tDCS sessions to maximize their benefits in this context when combined with exercise. Although there are already some studies that analyze the effects of adding tDCS to relatively short-duration exercise interventions (2-6 weeks) [24; 25; 26; 38], longer studies with follow-up assessments would be necessary to fully understand how this stimulation affects motor learning in participants. It is also important to recognize that if exercise alone produces strong effects, tDCS may not be the most effective complementary therapy for enhancing ankle dynamic balance, at least in the short term. Instead, its application may be more suitable for pathological populations who cannot adhere to demanding exercise programs. The results of the present study partially align with previous studies that have explored the combination of tDCS with specific motor control strategies [38; 43]. However, our study is the first to analyze its effect alongside a specific instability device, opening new research avenues regarding the use of more configurable and adaptable tools for specific needs. On the one hand, despite the apparent absence of benefits of integrating tDCS into the training program, enhancing motor learning by neuromodulation strategies remains an area of growing interest. Future research should focus on how different instability devices, in combination with tDCS, may influence neuromuscular control and balance training outcomes, exploring different protocols of application.