The effects of repeated sprint training with vs. without change of direction on measures of physical fitness in youth male soccer players

BACKGROUND: Fitness characteristics such as linear sprinting, repeated sprint ability, and change of direction (CoD) are important for male youth soccer players to maximize training safety and physical performance. We aimed to compare the effects of a 9-week repeated sprint training (RST) program, with and without change of direction (CoD) movements, on repeated sprint ability (RSA total time [RSAtotal], RSA best time [RSAbest]), CoD speed (505 CoD test), linear sprint speed (10-m and 20-m linear sprint), and aerobic endurance (AE; Yo-Yo intermittent endurance test level 1) in male youth soccer players. METHODS: During the in-season period, 20 soccer players were randomly assigned to a RST with CoD (RSTCoD) group (n = 10, age = 15.4±0.4 years) or a repeated linear sprint training group (n = 10, age = 15.6±0.3 years). Both training groups completed approximately two 15 minutes RST sessions per week, with the only difference between training programmes being the inclusion of one CoD movement during sprint repetitions for the RSTCoD group. RESULTS: The two-way ANOVA with repeated measures revealed a significant, moderate effect of time for RSAbest and RSAtotal (effect size [d] = 0.69 and 0.67, respectively). Likewise, significant, moderate-to-large effects of time were found for CoD (d=0.83), 10-m and 20-m sprint (d=0.68 and 0.67, respectively), and AE (d=0.66). No significant group × time interactions were observed for any measure of physical fitness (d=0.00 to 0.16). CONCLUSIONS: RST with and without CoD movements is equally effective in improving RSA total and best time, CoD speed, linear sprint speed, and AE in youth male soccer players