Accuracy of maturity prediction equations in individual elite male football players

Background Equations predicting age at peak height velocity (APHV) are often used to assess somatic maturity and to adjust training load accordingly. However, information on the intra-individual accuracy of APHV in youth athletes is not available. Aim The purpose of this study is to assess the accuracy of predication equations for the estimation of APHV in individual youth male football players. Subjects and methods Body dimensions were measured at least every three months in 17 elite youth male football players (11.9 +/- 0.8 years at baseline) from the 2008-2009 through the 2011-2012 seasons. APHV was predicted at each observation with four suggested equations. Predicted APHV was compared to the player's observed APHV using one-sample-t-tests and equivalence-tests. Longitudinal stability was assessed by comparing the linear coefficient of the deviation to zero. Results Predicted APHV was equivalent to the observed APHV in none of the players. A difference with a large effect size (Cohen'sd > 0.8) was noted in 87% of the predictions. Moreover, predictions were not stable over time in 71% of the cases. Conclusions None of the evaluated prediction equations is accurate for estimating APHV in individual players nor are predictions stable over time, which limits their utility for adjusting training programmes.