Effects of Eight-Week Game-Based High-Intensity Interval Training Performed on Different Pitch Dimensions on the Level of Physical Capacity and Time-Motion Responses in Youth Soccer Players.

This study aimed to assess the effects of two different pitch dimensions on physical fitness responses and time-motion characteristics in young soccer players during the in-season period. Thirty-nine participants were randomly assigned to two playing areas: a 90 m (PD90, n = 19) and a 180 m (PD180, n = 20) area per player. During the eight-week soccer-specific high-intensity interval training (HIIT) intervention, both groups performed four bouts of 5-a-side games (SSGs) in two different pitch dimensions of 5 min with 3 min active rest intervals between games. The heart rate (HR), total distance (TD) and distances covered while walking (WLK), jogging (JOG), low-speed running (LSR), high-speed running (HSR), and sprinting (SPR) were recorded during SSGs. Before and after the intervention, the following tests and variables were completed and evaluated: physical work capacity (PWC170), the Wingate anaerobic test, the lactate threshold (LT), 5-m, 20-m, and 30-m sprint tests. Significant between-groups differences were found post-intervention in PWC170 (p = 0.018, ES = 0.15) and the 5-m sprint (p = 0.002, ES = 0.24). Greater playing areas could be more beneficial in developing aerobic fitness, while SSGs on smaller pitch sizes improve the ability of short-distance accelerations.