Estimating Maturity Status in Elite Youth Soccer Players: Evaluation of Methods.

Abstract

To evaluate the concordance of predicted maturity status classifications (pre-, circa- or post-peak height velocity) relative to observed age at PHV in youth soccer players. Longitudinal height records for 124 male soccer players were extracted from academy records spanning the 2000-2022 seasons. Age at PHV for each player was estimated with the Super-Imposition by Translation and Rotation (SITAR) model. Players were classified as pre-, circa- or post-PHV using both ±1 year and ± 0.5 year criteria to define the circa-PHV interval. Maturity status was estimated with several prediction protocols: maturity offset (Mirwald, Moore-1, Moore-2), maturity ratio (Fransen), percentage of predicted adult height (PAH%) using the Khamis-Roche (KR) and Tanner-Whitehouse-2 (TW2-RUS) equations using several bands: 85%-96%, 88%-96%, 88%-93%, and 90%-93% for the circa-PHV interval, and visual evaluation of individual growth-curves alone or with PAH% based on KR and TW2-RUS. Concordance of maturity status classifications based on complete growth curves and predicted estimates of maturity status was addressed with percentage agreement and Cohen's kappa. Visual evaluation of the growth curves had the highest concordance (≈ 80%) with maturity status classifications (pre-, circa-, post-PHV) based on longitudinal data for individual players. Predicted maturity offset with the Mirwald, Moore-1 and Fransen equations misclassified about one- third to one-half of the players, while concordance based on PAH% varied with the band used, but not with the method of height prediction. Visual assessment of the individual growth curves by an experienced assessor provides an accurate estimate of maturity status relative to PHV. Maturity offset prediction equations misclassifies the majority of players, while PAH% provides a reasonably valid alternative.