ECSS Paris 2023: OP-AP30
INTRODUCTION: The pubertal growth spurt in youth soccer induces transient disruptions in neuromuscular control and physical performance. This phenomenon requires the monitoring of these physiological changes, optimizing tailored developmental programs to the specific maturity status of each player. The implementation of specific testing protocols could allow a deeper understanding of inter-team maturational variances. Therefore, this study aimed to evaluate the impact of maturity status on neuromuscular efficiency of the lower limbs in elite youth soccer players. METHODS: One hundred twenty-one youth soccer players (age: 9–15 years) from an Italian elite team, belonging to 7 age categories (from Under 10 to Under 16), were divided into three groups based on their maturity offset according to Mirwald’s method [1]: pre-PHV (n=63, < -1.0 years to PHV), circa-PHV (n=27, between -1.0 and +1.0 years), and post-PHV (n=31, > +1.0 years). Countermovement jump (CMJ) performance was assessed using two force plates (ForceDecks, FDLite V.2, VALD, Brisbane, Australia). Twenty force-time metrics extracted from the best trial, in terms of jumping height, of three attempts were analysed using a linear mixed model. Maturity offset was included as fixed factor, while the age category as random factor. RESULTS: Jumping height significantly differed (p<0.001) among pre-PHV (23.5±3.3 cm), circa-PHV (29.7±4.2 cm), and post-PHV (33.9±3.4 cm). A greater peak power emerged for post-PHV compared to pre-PHV (p<0.001; effect size [ES]=4.56) and circa-PHV (p<0.001; ES=1.95) and for circa-PHV compared to pre-PHV (p<0.001; ES=2.4). Countermovement depth was higher in post-PHV compared to pre-PHV (p=0.003; ES=1.54) and circa-PHV (p=0.028; ES=1.07). Higher eccentric duration (p=0.026; ES=0.97) and Reactive Strength Index (p=0.027; ES=1.44) emerged for post-PHV compared to pre-PHV. The ratio contraction time:eccentric duration was worse in the pre-PHV compared to circa-PHV (p=0.008; ES=0.7) and post-PHV (p=0.002; ES=0.81). No effect emerged for other metrics (i.e., concentric duration, asymmetry indexes, impulses indexes, landing and takeoff peak force). CONCLUSION: The current analysis demonstrated the influence of maturation not only on jumping performance, but also on specific force-time metrics obtained from a countermovement jump test. The superior performance of more mature players in the metrics related to the force-time profile (like eccentric contribution, the Reactive Strength Index, and countermovement depth) could explain a greater vertical jumping ability. These results were evident also across different age categories. Consequently, individual maturity status must be integrated into neuromuscular training programs to guarantee physical development, while preventing risk of injury, among youth players and support their soccer-specific performance. 1. Mirwald et al., 2002.
Read CV Salvatore MazzeiECSS Paris 2023: OP-AP30
INTRODUCTION: The Relative Age Effect (RAE) refers to an imbalance in birth-date distribution within youth categories, caused by age differences of up to one year between athletes born early and late in the same selection year. In athletics, this bias can influence performance assessment and talent identification. Existing correction methods mainly rely on additive linear models, assuming that RAE affects all athletes similarly. This study challenges this assumption by proposing a multiplicative recalibration model, based on the hypothesis that the effect of relative age depends on performance level. METHODS: All performances recorded by the French Athletics Federation between 2004 and 2025 were analyzed in U13 to U16 categories. For each athlete, the best performance per season was retained and linked to date of birth. Only disciplines, seasons and sexes with at least 100 athletes were included. For each sex, age group and discipline, models were trained on three consecutive seasons and applied to an independent fourth season. Two approaches were compared: (i) a traditional additive correction and (ii) a multiplicative correction in which adjustment depends on the athlete’s performance level. Model effectiveness was evaluated by examining the relationship between recalibrated performance and relative age in the test samples. Regression slopes were computed for the overall population and for higher-performing athletes (90th percentile). Slopes closer to zero indicate a better correction of RAE. RESULTS: A total of 387,568 performances were included, producing 1,247 independent test samples. For mean performance, both models provided similar corrections, with near-zero slopes (additive: 0.05, 95% CI −0.02 to 0.12; multiplicative: 0.09, 95% CI −0.01 to 0.19). For higher-performing athletes, the multiplicative model reduced residual age-related bias. At the 90th percentile, slopes were lower with the multiplicative model (0.11, 95% CI 0.08 to 0.14) than with the additive model (0.19, 95% CI 0.15 to 0.23), with a significant difference between approaches. CONCLUSION: While additive and multiplicative models similarly correct the average RAE, the multiplicative approach provides a more accurate adjustment for higher-performing youth athletes. These findings suggest that RAE is performance-dependent and that correction methods should account for this when used in evaluation and talent identification contexts.
Read CV Imad HAMRIECSS Paris 2023: OP-AP30
INTRODUCTION: Speed is a fundamental motor ability that influences soccer performance, particularly during youth development (1). Understanding segment-specific sprint performance is essential for designing age-appropriate training programs and monitoring neuromuscular development in youth soccer players. This study aimed to examine age-related changes in sprint performance in academy-level youth soccer players aged U10 to U19 using a multi-segment analysis of a single 30-m straight-line sprint in a cross-sectional design. Sprint times were analyzed for three segments: initial acceleration (0-5 m), maximal velocity segment (5-30 m), and total sprint time (0-30 m). METHODS: A total of 2,488 players from the Silesian Football Association (Poland) were assessed. Players performed a standard warm-up prior to testing, and each sprint was initiated from a standing start. Players performed three trials with 3-min recovery; best time was analyzed. Sprint performance was measured using a photocell timing system, enabling accurate split-time recording. Differences between adjacent age groups were analyzed using Welch’s t-test with Benjamini-Hochberg correction for multiple comparisons. We hypothesized that sprint performance would improve progressively with age. RESULTS: Significant improvements in sprint performance were observed across most age transitions, particularly between U10 and U15. The largest percentage improvements occurred in the 0–5 m segment between U12 and U13 (−6.3%) and in the 5–30 m segment between U10 and U11 (−6.3%), indicating segment-specific gains. Performance improvements plateaued in older categories (U17–U19), with negligible changes in certain transitions (e.g., 5–30 m: U16–U17, U18–U19), highlighting the flattening of speed development in late adolescence. CONCLUSION: These findings demonstrate a non-linear developmental trajectory of sprint performance in youth soccer. Acceleration improved most in mid-adolescence, whereas maximal velocity showed greatest improvements in early adolescence. Multi-segment sprint assessment provides valuable information beyond total sprint time and may support training optimization and talent identification in youth soccer (2). References: 1. Moran et al., 2018, J Sci Med Sport 2. Meyers et al., 2016, Med Sci Sports Exerc
Read CV Paweł ChmuraECSS Paris 2023: OP-AP30