Identification of Key Power Predictors of Bat Swing Speed in Youth Baseball Hitters Using PLS-SEM: Implications for Training Design

Abstract Park, H-S, Song, K-J, Lim, Y-E, Kim, J-Y, and Yoon, J-H. Identification of key power predictors of bat swing speed in youth baseball hitters using PLS-SEM: Implications for training design. J Strength Cond Res XX(X): 000–000, 2026—Bat swing speed (BSS) is a critical performance metric in baseball, reflecting efficient energy transfer through the kinetic chain. This study aimed to identify key predictors of BSS in youth baseball hitters using partial least squares structural equation modeling. Ninety-six male players (age: 13.9 ± 1.1 years) participated. Bat swing speed was measured using an inertial measurement unit during standardized tee-ball swings. Players then completed 3 medicine ball throw (MBT) tests—rotational medicine ball throw (RMBT), backward overhead medicine ball throw (BOMBT), and seated medicine ball throw—to assess explosive upper- and whole-body power. Lower-body power was evaluated through countermovement jump (CMJ) testing on a force platform, from which propulsive peak force, propulsive peak power, total impulse, rate of force development, and jump height were derived. Partial least squares structural equation modeling results showed that MBT significantly predicted BSS ( R 2 = 0.654, f 2 = 0.685, p < 0.001), with BOMBT and RMBT exhibiting the strongest factor loadings. Countermovement jump did not directly predict BSS but showed a significant indirect effect through MBT ( β = 0.284, p < 0.001), indicating a foundational contribution of lower-body power to swing-specific performance. These findings suggest that MBT, particularly BOMBT and RMBT, serves as a practical, sport-specific tool for assessing BSS in youth baseball players. Although CMJ is not a direct predictor of swing velocity, it may reflect underlying neuromuscular readiness. Integrated upper- and lower-body power profiling may enhance training strategies for youth athletes.