Sequencing effects of small-sided games and high-intensity interval training on physical and physiological performance of young soccer players during pre-season

Study aim: This experimental study investigated the sequencing effects of a small-sided games (SSG) protocol and highintensity interval training (HIIT) on the physical and physiological performance adaptation of soccer players, conducted over a fourteen-week of the pre-season.Materials and methods: Twenty-three young (aged 14 +/- 0.1 years) male soccer players from a club participating in nationallevel competitions were randomly divided into two groups (SSG + HIIT, n = 11 and HIIT + SSG, n = 12). The first group completed SSGs (5 vs. 5 + goalkeeper, 36 x 30 m) followed by HIIT (long interval at 60 to 75% of final velocity during 30-15 intermittent fitness test) training, while the second group performed HIIT training and then SSGs. Assessments were conducted at baseline and post-intervention for 10 m linear sprint, body fat percentage, countermovement jump (CMJ), change of direction speed (CODS), squat jump (SJ), and Yo-Yo intermittent recovery test (Yo-Yo IR).Results: A significant main effect of time was reported for 10 m linear sprint, CMJ, CODS, SJ, and Yo-Yo IR (p <= 0.001-0.010, eta p2 = 0.32-0.74). However, no significant group x time interaction were reported for any dependent variables (p = 0.433-1.000, eta p2 <= 0.01-0.03).Conclusion: The sequencing order of HIIT and SSG does not affect the performance outcomes in young male soccer players. Moreover, similar improvements can be expected in the 10 m linear sprint, CMJ, CODS, SJ, and Yo-Yo IR, irrespective of the exercise order. However, caution should be taken when interpreting the within-group improvements, as the study did not include a control group.