Effects of Two-Way Ballistic Versus Jump Squat Training on Explosive Strength and Neuromuscular Adaptations in Highly...

Maximal intended velocity (MIV)-based resistance training enhances explosive performance, yet it remains unclear whether different MIV modalities induce distinct neuromuscular adaptations. This study compared the effects of two-way ballistic (TWB) and jump squat (JS) training on explosive strength and neuromuscular characteristics in highly trained sprinters. Forty highly trained male sprinters (Tier 3) were randomly assigned to TWB (n = 20) or JS (n = 20). Both groups completed 12 training sessions (5 sets of 8 repetitions at 50%-55% 1RM) over 6 weeks. Pre- and post-tests included countermovement jump (CMJ), consecutive CMJ (CCMJ), 30-m sprint, isometric mid-thigh pull (IMTP), 6-s cycle sprint, vastus lateralis (VL) muscle architecture, and VL and biceps femoris (BF) activation during CCMJ performance. Both groups improved CMJ, CCMJ height, 30-m sprint, and 6-s cycle performance (p < 0.05), with similar increases in VL muscle architecture. TWB showed a greater IMTP 100-ms impulse improvement (ηp² = 0.25), while JS demonstrated greater improvements in the modified reactive strength index (RSImod; ηp² = 0.11). VL activation increased more after TWB than JS during take-off (p < 0.001, ηp² = 0.30) and during landing (p < 0.001, ηp² = 0.58). TWB and JS training both improved explosive performance through different neuromuscular pathways. TWB training enhanced early-phase force production and was associated with greater VL activation during take-off, whereas JS training preferentially improved reactive strength, likely reflecting SSC-related adaptations. These findings highlight that movement structure within MIV condition influences the direction of adaptation and should therefore be selected according to the specific performance qualities targeted in athletic training.