Does maturity status affect the mechanical response to high-speed running activities during international youth football match play?

Background Alterations in running mechanics during Football match play have been associated with an increased risk of injury for youth athletes. Objectives To assess maturity status on youth football players’ gait outputs during match play and to examine within- and between-match observations. Methods Players (N = 147) anthropometric data (14.35 ± 1.33 years, height 166.28 ± 8.80 cm, weight 56.24 ± 10.85 kg; Seated height 89.14 ± 5.28 cm) were collected prior to the start of the tournament during familiarisation sessions). All matches were monitored using foot-mounted inertial measurement units (F-IMU; Playermaker TM ) to quantify the gait metrics (contact time, flight time, stride length), with estimations of vertical stiffness presented. Data were analysed using a linear mixed model. Statistical significance was accepted as p ≤ 0.05, and effect size was calculated using partial eta-squared (η 2 ). Magnitude of effect sizes was small (0.2 < ES < 0.6), moderate (0.6 < ES < 1.2), large (1.2 < ES < 2) and very large (≥2). Results No significant between-game differences in gait symmetry or cadence across the tournament. Meaningful within-game increases in contact duration asymmetry emerging as early as the second phase of match play (p > 0.01; Moderate to large effect sizes). Post-PHV players demonstrated greater odds of exceeding a 5% asymmetry threshold compared with their Pre-PHV counterparts. Conclusion Within-match increases in contact time and contact duration asymmetry were evident during high speed running activities as early as the second phase of match play for all maturity groups. Future research should examine the longitudinal relationship between in-match gait asymmetry, biological maturation, and injury incidence.