Different External Cues Elicit Specific Kinetic Strategies During a Drop Jump in Well-Trained Adolescent Soccer Players

The purpose of this study was to examine how different external cues that focus on jump height and ground contact time influence kinetic outcomes from a drop jump (DJ) in well-trained young soccer players. Following familiarization, 21 adolescent male soccer players performed 2 DJ trials under 4 different cue conditions: a height cue instructed subjects to jump to the ceiling, a ground contact cue instructed subjects to get off the ground as fast as possible, a combined condition joined both cues together, whereas a neutral cue with no external focus was used as a control condition. The height and contact time cues elicited specific kinetic responses that were significantly different to other conditions (p < 0.05); the height cue increasing impulses (d = 1.17–1.21) and jump height (d = 0.68), with the contact cue shortening ground contact time (GCT) (d = 1.27), increasing vertical stiffness (d = 1.48) and increasing force (d = 1.20–1.36). When combining the height and contact cue, a combination of significant (p < 0.05) kinetic responses were also observed, albeit to a lesser effect. Specifically, the combined cue increased impulse (d = 0.71–0.76) and jump height (d = 0.57) compared with a contact cue and a height cue, increased reactive strength index (d = 0.34), force (d = 0.69–0.83), and vertical stiffness (d = 0.75) while also reducing GCT (d = 0.69). Practitioners working with well-trained adolescent soccer players can use different external cues to effectively influence the kinetic strategies employed during a DJ.