Impact of velocity intention and autoregulation on lower-body hypertrophy training: Adaptations in the load-velocity relationship and ballistic performance

This study compared the effects of percentage-based training (PBT), self-paced velocity-based training (SPVBT), and fast velocity-based training (FVBT; i.e., performing with maximal velocity intent) on the free-weight back squat load-velocity relationship (LVR) and countermovement jump (CMJ) performance in trained young males. Twenty-eight participants were randomly assigned to each group. For 10 weeks, participants performed two 4-week training cycles comprised of 3 weekly back squat sessions (70–85% of the one-repetition maximum [1RM]) with sets performed to momentary failure. Assessments were conducted at pre-, mid-, and post-training, and included vastus lateralis cross-sectional area (CSA), free-weight back squat 1RM, LVR parameters (slope, %1RM at zero mean concentric velocity [MCV] [LD0], MCV at 0%1RM [V0], area under the curve [Aline], MCV at 90 and 40%1RM, and CMJ parameters (height and average impulse force [IF]). LVR based load adjustments were performed at each session for the SPVBT and FVBT groups. CSA, 1RM, CMJ height increased similarly between groups and time points ( p  < 0.001, ES > 0.48). LD0 (%1RM) decreased similarly between groups at post-training ( p  = 0.043; ES: 0.12). Aline, Slope, V0, 90%1RM MCV, 40%1RM MCV and IF remained unchanged over time in all groups. However, V0, 40%1RM MCV and IF were higher for the SPVBT and FVBT groups, when compared to the PBT group at mid-training ( p  < 0.028; ES > 0.26). These findings indicate that large training volumes performed to momentary failure alter the shape of the LVR, irrespective of velocity intent and autoregulation. Additionally, while velocity expression with heavier loads is well preserved, applying VBT within this context may improve velocity output when lifting lighter relative loads. Finally, CMJ height can be improved during hypertrophy-focused training cycles, with increases in maximal strength playing a crucial role. However, relying on VBT seems beneficial as it magnifies force expression in unresisted lower-body ballistic contractions.