## 4 Discussion
### Implications for Soccer-Specific Training  
These findings have practical implications for soccer training programs. The high reliability of the tests supports their use in longitudinal athlete monitoring and individualized training design. Beyond reliability, the combination of metrics offers coaches a multi-dimensional view of an athlete's readiness, functional capacity, and adaptability to game-specific demands [20]. Coaches can use the data to identify the athlete's strengths and weaknesses in sprinting, agility, or reactive agility, and to tailor interventions to address specific performance gaps [8,17,21,34]. For instance, players with strong linear speed but lower reactive agility may benefit from drills that combine speed with perceptual and cognitive tasks, such as reaction-based sprints or small-sided games, emphasizing decision-making under pressure [3,32].  
The significant correlation between sprint and agility metrics also suggests the potential for transfer effects during training training [2,4]. This view aligns with performance periodization models used at elite levels, which stress the interconnectedness of mechanical, metabolic, and cognitive domains [21].  
In line with these principles, the Y-SRA test's inclusion of perceptual and cognitive components makes it particularly relevant for soccer, wherein players must rapidly process and respond to dynamic game situations. Such integration of cognitive loads during testing has been supported by recent research showing its role in enhancing ecological validity and functional relevance [2,20]. In the context of U12 players, incorporating reactive agility assessments into training and evaluation programs can accelerate the development of decision-making and anticipation skills, which are crucial for soccer performance [32]. Additionally, these tests provide insights into an athlete's readiness for competition, offering coaches a valuable tool for optimizing training load and recovery schedules.  
The moderate correlation between the MAT and the Y-SRA test (r = 0.387 *, \(p\) < 0.05) can be explained by the overlap in the physical and perceptual/cognitive demands of both tasks. Both tests measure agility, but they differ in how they challenge an athlete's motor and cognitive skills. The MAT primarily assesses an athlete's ability to change direction quickly and efficiently in a pre-determined pattern, which relies heavily on acceleration, deceleration, and the ability to maneuver through a course with minimal errors [34]. In contrast, the Y-SRA test incorporates a reactive component, wherein athletes must rapidly process external stimuli (such as light or auditory cues) and adjust their movements accordingly, adding a perceptual and cognitive layer to the assessment [3,17].  
This distinction suggests that the correlation between the two tests reflects both shared and unique components of agility performance. The moderate correlation indicates that while both tests measure similar aspects of physical agility, such as speed, change of direction, and coordination, the added element of reaction time and decision-making in the Y-SRA test likely reduces the strength of the correlation compared to tests without a reactive component [4]. Furthermore, the MAT, being a more traditional agility test, focuses on executing pre-planned movements, which might be less cognitively demanding than the Y-SRA test, wherein players must anticipate and react to unexpected stimuli in real time [15]. Thus, while both tests evaluate agility, the cognitive load imposed by the Y-SRA test likely accounts for the moderate correlation observed between the two measures. The relationship between the MAT and Y-SRA test suggests that developing both physical agility (as measured by the MAT) and reactive agility (as assessed by the Y-SRA test) is important for athletes, particularly in dynamic sports like soccer [1].