Factors Influencing Change of Direction Performance in Youth Soccer Players: Velocity-Time Profile Analysis of the Pro-Agility Test.

Abstract

Abstract: Nakamura, H, Yamashita, D, Nishiumi, D, Nakaichi, N, and Hirose, N. Factors influencing change of direction performance in youth soccer players: velocity-time profile analysis of the Pro-Agility test. J Strength Cond Res XX(X): 000-000, 2025-The purpose of this study was to assess factors influencing change of direction (COD) deficit (CODD) and total time completion (CODTT) in adolescent soccer players through velocity-time profile analysis of the Pro-Agility Test. We enrolled 71 junior high school male soccer players and measured the 20-m sprint time and CODTT of the Pro-Agility Test, calculating CODD by subtracting the 20-m sprint time from CODTT. In addition, 3-dimensional motion data were collected using a markerless motion capture system during the Pro-Agility Test. Each section (5 m in the first, 10 m in the second, and 5 m in the third) was divided into acceleration and deceleration phases based on center of mass (COM) velocity, which were further divided into early and late halves. The mean COM acceleration during the acceleration phase (Acc) and deceleration during the deceleration phase (Dec) were calculated. Stepwise multiple regression analysis was performed to identify phases affecting CODTT and CODD. Statistical significance was set at p < 0.05. Total time completion of a COD task was explained by the second early Acc (β = -0.500), second late Dec (β = 0.433), and 20-m sprint time (β = 0.226) (adjusted R2 = 0.858), whereas CODD was explained by the second late Dec (β = 0.561) and second early Acc (β = -0.271) (adjusted R2 = 0.459). Maturity offset significantly correlated with CODTT (r = -0.456) but not with CODD (r = -0.119). The results indicated that deceleration and reacceleration during the Pro-Agility Test can be evaluated in adolescents by combining CODTT and CODD.