Is change of direction deficit task-specific in youth soccer players? A preliminary analysis

Purpose This study investigated whether the change of direction deficit (COD deficit) behaves as a task-specific construct across multiple field-based tests in regional-level male U17 soccer players. Methods Eighteen regional-level male U17 soccer players completed linear sprint tests over 20 m, together with three COD tests: The Modified 505 test, the Pro-Agility test, and a 90 °COD test. COD deficit was calculated as the time difference between linear sprint and COD performance. Results Raw performance time differed significantly across conditions, F(4, 68) = 325.93, p < 0.001, ηp2 = 0.95, with all COD tests producing longer times than linear sprinting. COD deficit also differed significantly across tests, F(3, 51) = 267.82, p < 0.001, ηp2 = 0.97, with the largest deficit observed in the Pro-Agility test, intermediate values in the Modified 505Agility test, and the smallest deficit in the 90 °COD test. Inter-test correlations for COD deficit were low to moderate, whereas associations with linear sprint performance were weak. Conclusion COD deficit showed task-dependent behavior across tests, suggesting that its expression may vary according to the mechanical and coordinative demands of each protocol.