Comparison of running performance between official match and friendly match in elite youth football players: A case study

This study examines the impact of age (U17/U21) and match type (friendly/official) on external load indicators in elite youth football players during key developmental transitions. Twenty-nine male players (U21: n = 13; U17: n = 16) from a Chinese professional club were tracked over a full season (U17: 37 matches; U21: 29 matches) using 10 Hz GPS. Data were analyzed using Mann-Whitney U tests, Cliff's Delta (δ), and Hodges-Lehmann median differences. In official matches, all external load indicators for U21 players were significantly higher than U17s, with the largest effect size in running distance at 15–20 km/h (δ = 0.593) versus total distance (δ = 0.202). In friendly matches, U21s remained superior in distance >25 km/h, accelerations, distance 15–20 km/h, and maximum speed, though the max speed gap narrowed by 21.94% compared to official matches. Except for maximum speed and distance >25 km/h, U21 external loads were significantly higher in official matches than friendly ones, particularly regarding deceleration. Conversely, U17 running distances at 15–25 km/h were significantly higher in friendly matches (p < 0.05). Therefore, this study found that U21 and U17 players performed better in official matches than in friendly matches; deceleration control ability is a key indicator of U21 players’ adaptation to high-intensity competitions; the unique negative correlation pattern of ‘medium-high intensity load-match type’ in the U17 group may be related to the decline in running performance caused by psychological pressure, conservative tactics or delayed decision-making in official matches.