Exerting force at the maximal speed drives the increase in power output in elite athletes after 4 weeks of resistance training

Purpose: In the present study, we examined how a 4-week intervention of maximal intended velocity (MIVRT) and controlled velocity resistance training (CRT)-induced task-specific responses in expert individuals. Methods: Twenty elite athletes were randomly assigned to either a MIVRT (n = 10) or CRT (n = 10) group, both following the same volume–load training based on the back-squat three times a week but with different intentions in moving load (force–exertion speed). We assessed one-repetition maximum (1RM), mean propulsive velocity (MPV), and mean propulsive power (MPP) using a progressive-loading test before and after the intervention. A linear position transducer was used to monitor propulsive velocity in training and testing sessions. Results: Both groups significantly increased their 1RM (CRT: + 12.3%, p < 0.001, d = 0.39; MIVRT: + 12.5%, p < 0.001, d = 0.45). Only the MIVRT group showed a significant improvement in MPV (p < 0.01) across different stepping loads, while both groups improved in MPP (MIVRT: + 22.4%, p < 0.001, d = 0.54; CRT: + 8.1%, p = 0.04, d = 0.17). Conclusions: MIVRT induced significant adaptations in MPV and MPP at various loads (%1RM), underlining its specificity in targeting these parameters. Despite similar enhancements in 1RM, the distinct training protocols suggest that strength gains may stem from either maximal intent in moving loads or longer times under tension. This study highlights the role of execution speed in optimizing power outcomes, emphasizing task specificity as paramount to elicit physiological adaptations in chronically strength-trained individuals.