The influence of growth and maturation on physical performance and selection bias in academy female football players

Adolescent growth and maturation vary widely between individuals which presents challenges for the development of physical capacities and complicates talent identification in youth female football players. Hence, this study investigated the influence of growth and maturation on physical performance and selection bias within a professional youth female football academy. Fifty-six female academy footballers completed assessments of anthropometry (stature, seated height, body mass), linear sprint speed (10 m and 30 m), change of direction speed (modified-505), lower body power (countermovement jump), lower body reactive strength (10-5 repeated jumps), and hip abductor relative strength. Players were grouped into maturation status (pre-, circa-, post-peak height velocity [PHV]) and maturation timing (early, on-time, late), following the estimation of biological maturation. Significant moderate correlations were observed between maturity offset and 10 m (p = 0.014; r = -0.33), 30 m (p<0.001; r = -0.44) and modified-505 time (p=0.002; r = -0.41). No significant correlation was found between maturity offset and countermovement jump (p = 0.164; r = 0.19), 10-5 repeated jump (p = 0.323; r = 0.14) and relative hip abduction strength (p = 0.5; r = -0.04) performance. Players post-PHV recorded superior sprint and change of direction performance, but not lower body power, reactive strength, or relative hip abduction strength compared to players circa-PHV. Both the distribution of birthdates (p = 0.01) and maturation timing (p<0.001) were uneven across the academy, and a relative age effect was present. Our findings establish novel physical performance reference points by maturation status and illustrate the complexities inherent in adolescent athletic development. The presence of a selection bias within the academy warrants key consideration to biological maturation and relative age in the successful identification of talented youth female footballers.