Acute Metabolic, Mechanical, and Perceptual Responses to Curve Versus Linear Repeated-Sprint Training in Highly Trained Youth Soccer Players.

PURPOSE: This study aimed to (1) evaluate the acute metabolic, mechanical, and perceptual responses to curve versus linear repeated-sprint-training (RST) protocols in highly trained youth soccer players and (2) analyze whether the sprint trajectory influences the time course of recovery following RST protocols.

METHODS

Twenty-seven highly trained youth soccer players randomly performed 2 RST protocols (12 × 17 m with 15-s intervals) with different trajectories: linear or curve (radius of 9.15 m). Blood lactate concentration, countermovement-jump height, modified reactive strength index, and myotonometric measurements of the biceps femoris long head (stiffness, frequency, and decrement) were assessed before and 0 minutes, 5 minutes, and 24 hours after the protocols. Likewise, best and average sprint velocities were recorded in both protocols, and perceptual responses were evaluated using Borg and Hooper scales.

RESULTS

Linear RST showed higher velocity outputs than curve RST (P < .001). No significant time × condition interactions were observed for blood lactate concentration, countermovement-jump height, modified reactive strength index, time to takeoff, or myotonometric measurements (all P < .05), except for right-leg stiffness (P = .047), which significantly increased from 0 minutes to 24 hours only after curve RST (P < .05). Additionally, players also reported poorer sleep quality (P = .045) following the curve RST.

CONCLUSIONS

Overall, these findings suggest that the acute metabolic, mechanical, and perceptual demands of RST are not trajectory dependent. Therefore, strength and conditioning coaches can use both trajectories to address soccer-specific sprint demands in elite youth soccer players.