In the Reign of Velocity: Ballistic Training Enhances Rapid Force Production in Chronically Strength-Trained Athletes

Purpose: Rapid force production relies upon neuromuscular mechanisms differing from those underlying maximal strength. In chronically strength-trained individuals, specific adaptations in rapid force variables (RFVs)-both absolute and normalized to maximal force capacity-following resistance training with ballistic versus controlled contractions remain underexplored. Therefore, we examined whether improvements in maximal propulsive power (MaxPP) coincide with RFV responses, specifically, rate of force development (RFD) and impulse. Methods: Ten elite athletes (female n = 5) underwent maximal-intended-velocity (MIV) training and were compared with 10 (female n = 5) elite athletes performing moderate-velocity (MOV) training lasting 4 weeks. One-maximum repetition (1RM), MaxPP, and RFVs (RFD and impulse) were assessed at baseline and following 4 weeks of training. Results: Both groups exhibited significant increases in 1RM (MIV: +13.9 kg, P < .001; MOV: +14.4 kg, P < .001). Although absolute MaxPP, RFD, and impulse improved in both groups, only the MIV group showed significant enhancements when normalized to 1RM (MaxPP: +13 W %1RM-1, P = .002; RFD: +61% 1RM·s-1, P = .004; impulse: +5% 1RM·s, P = .01). In contrast, MOV training reduced normalized MaxPP (-3 W %1RM-1, P = .04) and RFD (-15% 1RM·s-1, P = .02), with no significant change in impulse. A positive association was observed between improvements in MaxPP and RFD (P < .01). Conclusions: These findings recognize ballistic contractions as the primary driver of improvements in RFVs among chronically strength-trained individuals. The parallel increase in MaxPP and RFD underscores the intrinsic relationship between the physiological capacity for rapid force generation and the resultant contraction speed, with the velocity demands placed on the neuromuscular system during resistance training governing these adaptations.