## 4 Discussion
### Correlations Between Linear Speed, MAT, and Y-SRA  
One of the key findings from this study is the strong correlation between the 15 m sprint performance and the total Y-SRA time (r = 0.74). This result highlights the interconnected nature of linear sprinting and reactive agility in U12 soccer players. Such findings are consistent with the previous literature showing that physical performance attributes often interact strongly at younger ages, due to the ongoing neuromuscular development and maturation of such athletes [19,20]. Similar correlations have been reported in previous research, indicating that both physical and perceptual cognitive attributes contribute significantly to performance in field-based sports, such as soccer [3,32]. This strong relationship can be attributed to shared physical determinants, such as lower-body strength, acceleration capacity, and efficient mechanics for braking and re-acceleration, all of which are crucial for both straight-line sprinting and directional changes [1,2]. In particular, U12 players benefit from their ongoing neuromuscular development, which enhances their ability to perform rapid and efficient movements [3,32]. At the age of 12, children are at a critical phase of motor development and neuromuscular maturation [30,33]. Motor skills, such as coordination and dynamic balance, improve rapidly at this stage, as confirmed by studies examining the effects of structured training in  
Figure 5: Links between sprint speed, agility, and reactive decision making in U12 soccer players. diverse youth populations [22]. These enhanced motor abilities facilitate both linear sprint performance and the capacity to quickly change direction. Furthermore, elite-level research has shown that in older players, the ability to sustain high-intensity actions depends on their efficient mechanical and perceptual adaptations, which may originate from foundational developments at earlier stages [20]. Additionally, this age group undergoes physiological adaptations, including increased muscular strength, improved postural control, and better dynamic balance [1]. These factors contribute to superior performance in tasks demanding acceleration, deceleration, and rapid directional changes, which are fundamental to both sprinting and reactive agility [30]. Taken together, these developmental and physiological characteristics likely underpin the observed correlation between sprint speed and Y-SRA performance, emphasizing the importance of neuromuscular development and shared physical capacities in young soccer players. In addition to physical components, reactive agility integrates perceptual and cognitive demands, including the ability to process external stimuli and execute appropriate motor responses [15]. The Y-Shaped Reactive Agility test replicates the decision-making and reaction-speed requirements of soccer, making it a valid tool for evaluating game-specific agility [34]. The observed correlation suggests that the maximal speed over 15 m contributes significantly to the ability to execute reactive agility tasks, as the momentum generated in longer sprints facilitates smoother transitions during directional changes. The correlations obtained between the Y-SRA test and the three sprint distances (5 m, 10 m, and 15 m) reveal a clear trend, with the 15 m sprint showing the highest correlation. This may be due to the fact that longer sprints integrate more complex motor and perceptual demands, including speed maintenance, coordination, and adaptive movement control. This finding suggests that longer sprints are more strongly related to reactive agility performance than shorter sprints. The higher correlation with the 15 m sprint can be explained by the combination of physical and neuromuscular demands it imposes, which are more aligned with the requirements of the Y-Shaped Reactive Agility test.