## 4 Discussion  
The present study aimed to analyze the acute effects of single-bout high-intensity functional training (HIFT) and moderate-intensity functional training (MIFT) on cognitive function, stress, and anxiety. The results showed significant improvements in executive function, specifically in the mean response time in both sessions, although only the HIFT group showed significant improvements in correct responses. No significant differences were observed for the other executive function variables. In terms of attention, both groups showed significant improvements in concentration, with a large effect size. The HIFT group demonstrated improvements in both concentration and attention, while the MIFT group only showed improvements in concentration. Regarding memory, no significant differences were found for either group. For concerning anxiety, only the MIFT group showed significant improvements in state anxiety (\(p\) = 0.003), with no changes in trait anxiety or stress in either group. We would like to highlight that, throughout the discussion, due to the scarcity of scientific evidence from studies similar to that conducted in the present manuscript, we will compare and contrast our results with those from similar studies in different populations or comparable populations, as well as with interventions related to the theme of the manuscript. Regarding HIIT, it has been associated with improvements in executive function (EF) [38,39]. A systematic review suggested that HIIT may have a positive effect on EF, with 61% of studies showing a positive effect and 39% showing no or negative effects [30]. Figure 3: Comparison of correct responses, pre- and post-intervention, based on the type of training performed. Abbreviations: HIFT (high-intensity functional training); MIFT (moderate-intensity functional training); \({}^{*}\)\(p\) < 0.005. A recent study showed improvements in attention and cognitive flexibility following a four-week HIIT program involving overweight adult women [39]. However, further research is needed to confirm these findings and explore the long-term benefits of HIIT on cognitive function. Other studies suggest the importance of identifying factors such as age, gender, and fitness level [40]. On the other hand, attention, measured using the d2 Test, showed significant improvements in the HIFT group, supported by the results of previous studies in different populations. A study with children showed improvements in attention following a 10 min HIIT training session [41]. Another study with young adults found benefits in regards to executive function and attention after HIFT and MICT (moderate-intensity continuous training) [24]. On the other hand, regarding the effects on concentration, also measured with the d2 Test, our study showed significant acute improvements after the session in the HIFT group. This result is also observed in older adults, but in this case, after a 3-month HIFT intervention, highlighting that no improvements in attention were found [42]. Regarding working memory, measured with the Word Recall Test, no significant results were found, which aligns with studies that do not show exercise effects on working memory immediately after exercise [43; 44]. However, some studies have reported improvements with HIIT and MICE (moderate-intensity continuous exercise) programs [45]. Finally, we would like to highlight a study that found significant improvements in working memory after a single session of HIFT compared to the results for another group that walked at 60% of their heart rate reserve [46]. Concerning the construct of anxiety, the MIFT group showed significant improvements in state anxiety (\(p=0.003\)), with no changes in trait anxiety in either group. This finding is also observed in previous studies that show a reduction in anxiety following exercise programs, although without considering the intensity of the exercise [47; 48]. Regarding the variable of stress, no significant improvements were obtained.