Efficacy of depth jumps to elicit a post-activation performance enhancement in junior endurance runners.

To determine the effect of performing depth jumps (DJ) pre-exercise on running economy (RE) and time to exhaustion (TTE) at the speed associated with maximal oxygen uptake (sV˙O ) in a group of high-performing junior middle-distance runners. Randomized crossover study. Seventeen national- and international-standard male distance runners (17.6±1.2years, 63.4±6.3kg, 1.76±0.06m, 70.7±5.2mLkg min ) completed two trials. Following a 5min warm-up at 60% V˙O , participants performed a 5min run at 20%Δ below oxygen uptake corresponding with lactate turn-point to determine pre-intervention RE. Participants then completed either six DJ from a box equivalent to their best counter-movement jump (CMJ) or a control condition (C) involving body weight quarter squats. After a 10min passive recovery, another 5min sub-maximal run was performed followed by a run to exhaustion at sV˙O . Compared to the C trial, DJ produced moderate improvements (-3.7%, 95% confidence interval for effect size: 0.25-1.09) in RE, which within the context of minimal detectable change is considered possibly beneficial. Differences in TTE and other physiological variables were most likely trivial (ES: