## 4 Discussion
Furthermore, only students with poorer physical fitness and those who are more motivated show significant improvements in physical education classes [29; 43]. Therefore, when implementing fitness improvement programs in physical education classes, individual student needs must be considered [44; 45]. Unfortunately, in the present study, student motivation and satisfaction variables were not evaluated. Moreover, physical fitness can be enhanced through a variety of programs and content, as demonstrated by [46], which shows that \"outdoor\" natural environment activities can improve fitness, as well as exergames (Wii or Xbox), as has been published [47]. This improvement in physical fitness can be maintained, for instance, through activities involving body expression, as evidenced by [48]. Identifying the motivating methodologies and interventions that promote the adherence to physical activity both inside and outside the classroom is essential. This includes increasing motor engagement times and conducting moderate to vigorous intensity activities in physical education classes [23]. Although there is limited evidence on the optimal intensity and duration of physical education classes [24], methodologies such as HIIT have emerged, yielding significant improvements in cardiorespiratory fitness and other areas of physical fitness [8]. Moreover, a meta-analysis [25] compared various PE interventions and the findings indicate that HIIT is the most effective intervention in reducing BMI, and improving VO\({}_{2}\) max and sprint performance. Also, some studies [49; 50] have reported that HIIT enhances performance in the 20 m sprint. These authors highlight anaerobic power and leg muscle strength as the primary determinants of sprint performance. Recent research [51; 52] further suggests that targeted HIIT and strength training are critical for modifying these key factors. Specifically, endurance-focused HIIT and speed-based HIIT have been shown to be particularly effective in improving these performance-related attributes. Moreover, It has been demonstrated that HIIT is particularly effective in enhancing shuttle running performance and VO\({}_{2}\) max [25]. This finding aligns with the results of a meta-analysis [53], which also highlighted the superior impact of HIIT on these fitness parameters. The observed improvements are likely attributable to beneficial exercise-induced mitochondrial adaptations, along with enhanced blood capillarization, increased oxidative enzyme activity and improved oxygen transport within the muscular system [54]. In our study, the experiments carried out an intervention based on strength or an endurance program focused on HIIT protocol, engaged in 8 weeks of specialized training within the PE class schedule during school hours. Previous studies have shown that age-related resistance training can have a favorable influence on the psychological well-being of school-age youth, provided that self-improvement and enjoyment remain central to the training program [55]. The findings of the present study are limited to the context of physical education classes and the effects of the intervention on physical fitness and cognitive performance. As such, any conclusions must remain within the scope of these outcomes and with this type of intervention, always taking into account correct physical education planning [30]. This involves meaningful learning that can be applied in their daily lives, providing opportunities and tools to occupy their leisure time. It has been published that this will encourage students to be more active during their free time [31]. Our study has some limitations that should be considered. First, the research was conducted in a school context, which introduces additional variables that can affect outcomes, such as the variability in program implementation and differences in student engagement. The short-term intervention (8 weeks, 16 sessions) was derived from the school calendar itself, as there are often holidays that interrupt interventions.