Interrelationships and Shared Variance Among Three Field-Based Performance Tests in Competitive Youth Soccer Players

<b>Objectives:</b> Field-based testing is commonly used to evaluate key physical qualities related to soccer performance. However, limited research has examined the degree of shared variance among measures of aerobic capacity, change of direction (COD), and explosive power in youth athletes. This study investigated the relationships between the 20 m shuttle run (20MSR), T-test (TT), and vertical countermovement jump (CMJ) to determine their unique and overlapping contributions to each other's performance in competitive youth soccer players. <b>Methods:</b> Twenty-five competitive male youth soccer players (13.7 ± 0.8 years) completed standardized assessments of TT, CMJ, and 20MSR during pre-season evaluations. Pearson correlations and hierarchical multiple regression analyses were used to examine associations and independent variance explained among the performance measures. <b>Results:</b> Large, significant correlations were observed between TT and CMJ (r = -0.65, <i>p</i> < 0.001), TT and 20MSR (r = -0.59, <i>p</i> < 0.001), and CMJ and 20MSR (r = 0.53, <i>p</i> = 0.007). CMJ explained 42.3% of TT variance, whereas adding 20MSR did not significantly improve model fit (ΔR² = 0.087, <i>p</i> = 0.062). Across models, aerobic capacity did not contribute significant unique variance beyond neuromuscular performance. <b>Conclusions:</b> COD and lower-body power share a common physiological foundation in youth soccer athletes, while aerobic capacity represents a distinct performance domain. When field tests are administered under applied conditions typical of youth soccer environments, TT and CMJ demonstrate substantial shared variance, whereas 20MSR remains largely independent. Therefore, the findings support the continued use of multi-modal testing batteries in practice.