The Effects of Drop Jumps on the Load-Velocity Profile of the Deadlift

The primary aim of this investigation was to examine the effects of three drop jumps (DJ) on mean velocity (m/s) of subsequent deadlifts at various percentages of 1 RM. A secondary exploratory aim was to evaluate whether protocol order, sex, and relative strength moderated the effects of the DJ on deadlift velocity. Twenty-two resistance-trained participants (n = 13 males, n = 9 females; 26.1 ± 2.9 years, 168.4 ± 11.05 cm, 81.2 ± 18.1 kg), underwent a one repetition max (1RM) deadlift assessment and participated in a randomized cross-over design with two experimental sessions. The experimental sessions consisted of a deadlift load-velocity profile test, including 5 repetitions at 40%, 3 repetitions at 60%, and a single repetition each at 70%, 80%, and 90% of their tested 1RM. In the intervention protocol, participants performed 3 DJ repetitions between each deadlift set, while in the control condition, participants only rested for the designated time. A mixed factorial ANOVA was conducted with condition and load as within-subjects factors and sex, relative strength, and protocol order as between-subjects factors. No significant condition × load interaction was observed between the intervention and control protocols (F_2.91,113.36 = 0.48, p = 0.69, η² = 0.01). Additionally, there were no effects for protocol order, relative strength, or sex on the intervention effect were observed (p > 0.05). Visual inspection of individual responses revealed substantial inter-individual variability, with participants demonstrating increases, decreases, or no change in deadlift velocity following DJ implementation. In conclusion, this study revealed that the integration of DJs between sets did not consistently affect deadlift mean velocity across different intensities. The responses of participants varied considerably, encompassing increases, interference effects, or no discernible response.