Effects of change of direction during high-intensity interval training on physical performance in young football...

This study aimed to determine the differences between high intensity interval training (HIIT) with turns and HIIT without turns and what effects these types of HIIT will have on speed, change of direction (COD) speed and agility in young football players during transition period. The participants were 57 young football players (Age: 15.7 ± 1.5 years; Height: 179.2 ± 5.2 cm; Body mass: 69.4 ± 6.6 kg), randomly assigned to a group that performed HIIT with linear sprinting (HIIT_linear; N = 28) and another group that performed HIIT training with COD (HIIT_COD; N = 29). Players were tested for speed (5,10, 20 m), COD speed and agility. Both groups conducted the program during four weeks with two sessions per week. Results: Significant positive changes within both groups were observed for the linear sprint 5, 10, and 20 m and the Illinois test (p < 0.05). No significant differences were found for COD speed and reactive agility, either between or within the groups (p > 0.05). Conclusions: HIIT showed significant improvements in linear sprints and Illinois agility test after both types of HIIT training.