The Effects of Selected Mechanical and Anthropometric Variables on Change-of-Direction Ability in National Team-Level Youth Basketball Players

Change-of-direction (COD) ability is a key determinant of performance in youth basketball, yet the relative contribution of braking, re-acceleration, trunk motion, and body composition remains unclear. Thirty-two male U18 national-team level players (17.6 ± 0.7 y; 194.8 ± 4.5 cm; 89.1 ± 9.4 kg) completed whole-body and segmental DEXA assessment, bilateral countermovement jump (CMJ) testing and a 505 agility test (505) instrumented with a local positioning system. Mean COD times were 2.36 ± 0.09 s (505) and 1.84 ± 0.08 s (303), with maximal deceleration (DcMax) of −7.26 ± 0.52 m·s−2. Paired t-tests showed no significant differences between right- and left-leg turns for any variable (all p > 0.25), indicating symmetrical COD performance. General linear models revealed that DcMax was the only consistent predictor of COD time (505: R2 = 0.53, F (7,24) = 3.91, p = 0.006, partial η2 = 0.31; 303: R2 = 0.49, F(9,22) = 2.34, p = 0.050, partial η2 = 0.34), with a smaller additional effect of approach speed for the 303 segment (p = 0.049). Body-composition indices and CMJ variables showed only weak, non-significant correlations with COD time (|r| 0.05), and neither centripetal force nor trunk angular speed was associated with performance. These findings indicate that high-intensity braking capacity, rather than muscle mass or jump power per se, is the primary mechanical determinant of COD in elite youth basketball, suggesting that deceleration-focused training should be prioritized in performance development.