Unilateral Flywheel versus Traditional Split-Squat Exercise for Post-Activation Performance Enhancement: Effects on Jump, Change-of-Direction, and Sprint Performance in Junior Basketball Players

Post-activation performance enhancement strategies are increasingly used to improve explosive performance in team sports. This study examined the acute effects of unilateral flywheel eccentric overloading and traditional split-squat conditioning on vertical jump (VJ), change-of-direction (COD), and sprint performance in junior basketball players. Eighteen male players were randomly assigned to a flywheel group (FLY; n = 9; age 17.5 ± 0.53 years; body mass 76.0 ± 5.9 kg) or a traditional resistance group (TRAD; n = 9; age 18.0 ± 0.47 years; body mass 81.8 ± 8.1 kg). The FLY group performed unilateral split squats using a flywheel device (0.025 kg·m² inertia), whereas the TRAD group performed Bulgarian split squats with free weights at 80% one-repetition maximum. Each group performed two sets of six repetitions. Performance was assessed at baseline and at the 2nd, the 4th, the 8th, and the 15th min following the conditioning activity. A significant group × time interaction was observed for COD performance (p = 0.001). Post-hoc comparisons showed that T-test performance improved in the FLY group at the 8th min (−5.7%, Cohen’s d = 0.83) and the 15th min (−8.4%, d = 1.12) relative to baseline, whereas no significant changes were observed in the TRAD group. No significant interactions were found for VJ or sprint performance. These findings suggest that the unilateral flywheel split-squat protocol acutely enhanced COD performance more than the traditional split-squat protocol. Performance improvements occurred between the 8th and the 15th min following the conditioning activity, suggesting that flywheel-based priming may represent a practical strategy for short-term COD readiness in basketball.