Abstract details
| Abstract-ID: | 1919 |
| Title of the paper: | Nonlinear Age and Maturation Effects on Jump and Isometric Strength Performance in Elite Youth Footballers |
| Authors: | Sayer, A., Howatson, G. Moran, J. Howe, L. Tallent, J |
| Institution: | University of Essex |
| Department: | School of Sports, Rehabilitation, and Exercise Sciences |
| Country: | United Kingdom |
| Abstract text | INTRODUCTION: Systematic physical profiling underpins athlete monitoring and talent identification in elite youth football; however, limited research has described how multiple neuromuscular qualities vary across the full academy pathway. This study aimed to characterise age- and maturation-related differences in jump and strength performance in players from a professional English Category 2 academy and to provide normative benchmarks for applied practice. METHODS: One hundred and thirty-two trained male players (U9–U21) completed a pre-season battery including countermovement jump (CMJ), drop jump (DJ), iso-prone hamstring pull, 60° isometric hip adduction and abduction, and isometric belt squat (age-group dependent). Between-group differences were examined using one-way ANOVA with Tukey post hoc tests. Developmental trajectories were modelled using generalised additive models (GAMs) with cubic regression splines, with chronological age and percentage of predicted adult height (PAH%) entered as continuous predictors. Segmented regression identified breakpoints in performance trends. RESULTS: Significant between-group differences were observed for all variables except absolute and relative belt squat peak force (p < .05). CMJ jump height (?² = .702) and relative concentric peak power (?² = .540) demonstrated the largest age effects. Absolute isometric peak force increased with age; however, relative values were attenuated, indicating strength gains largely paralleled increases in body mass. Age-based GAMs revealed nonlinear improvements in CMJ jump height (adj. R² = .67) and concentric peak power (adj. R² = .61), characterised by rapid gains from ~9 to 17 years followed by plateauing. DJ reactive strength index (RSI) and flight time (FT) showed similar nonlinear increases (adj. R² = .57-.61), while contact time (CT) decreased modestly (adj. R² = .17). Breakpoints occurred at ~17.5 years for CMJ and DJ height-based variables and ~15.8 years for CT. When modelled against PAH%, CMJ jump height (adj. R² = .69) and concentric peak power (adj. R² = .65) increased progressively toward 100% PAH without plateauing. RSI and FT during DJ showed comparable maturation-dependent increases (adj. R² = .52-.57), whereas CT showed a weaker inverse association (adj. R² = .17). Relative eccentric peak force showed a gradual trajectory, with lower explanatory power in both models (adj. R² = .23-.26). CONCLUSION: Lower-body power and reactive strength exhibit pronounced nonlinear improvements across adolescence, whereas relative strength measures show limited discriminatory capacity between age groups. These age- and maturation-specific benchmarks provide applied context for monitoring progression within elite youth football pathways. |
| Topic: | Training and Testing |
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