Variation in exercise intensity during typical training drills in youth footballers measured via GPS tracking devices

PURPOSE: The present study aims to investigate the between-athlete and within-athlete variation in intensity occurring during various small-sided games (SSG) formats to determine their relevance within soccer specific drills. METHODS:19 youth male football players (age:14.0 ±1.0 y, height: 1.6 ±7.4 m, body mass: 54.5 ±7.5 kg) were monitored during an 8-week period two times per week. The first two weeks consisted of a familiarization phase followed by 6 weeks of monitoring. Subjects performed a standardized warmup prior to completing various formats of SSG games (3 vs. 3 and 6 vs. 6). Each SSG were performed with a duration of 2 x 4 minutes interspersed with 3 minutes rest. All players were equipped with a player tracking device (OptimEye S5, Catapult Sports, Australia) consisting of both a GPS-TD collecting data at 10 Hz and anIMU measurement unit collecting data at 100 Hz. Selected measurements include PlayerloadTM (accelerometer-based measurement of external training load), PlayerloadTM 2D (excluding vertical axis) High intensity events (HIE) which is the combined measurement of accelerations, decelerations, and changes of direction, Total distance, meter per minute and low intensity running (LIER) which is running performed at speeds lower than 11.0 km/