## 2 Materials and Methods  
### Experimental Design  
Maturity process can strongly influence the development of physical attributes of basketball players and their individual game performance. The vast majority of studies that addressed this topic used the Mirwald equations, although using different cut-off values of APHV (international, national or mean average sample) and classification time which, may or may not, influence the obtained results. Thus, this is an observational and analytical study designed to test if physical and game performance differences between maturity contrasting groups were reliant on the cut-off values of APHV selected.  
The protocol included two different studies: Study 1, with a sample of 439 boys aged between 11-16-years of age, was designed only to establish a Portuguese boys cut-off points of APHV (Figure 1). The Preece Baine 1 growth model was adjusted to the sample (study 1) mean profile. Study 2, included a sample of 172 Portuguese elite regional basketball players aged 13-14-years of age and was designed to compare the morphologic, physical and individual game performance across maturity timing categories. Anthropometric measures were measured following the International Society for the Advancement of Kianthropometry (ISAK) protocol [22]. To avoid the influence fatigue has on players' results, morphologic and fitness measurements took place on the first day of the tournament. Before the fitness tests all subjects performed a 20-min standardized warm-up routine, and between tests the players were allowed 10-min passive rest. Each participant was verbally instructed and encouraged to give his maximum effort. All players completed seven fitness tests, from which nine variables were collected for analysis (Table 1). For more detailed description of the procedures see [PERSON] and coauthors (2020) [23].  
The participants (study 2) were assigned to three maturity timing groups based on differences between the reference APHV and their estimated APHV. We used three references for APHV: (1) the international reference used in [PERSON] study, 13.81 years; (2) our national (study 1) reference, around 13.45 years, and (3) the mean value of the studied sample (study 2) with an estimate average APHV around 13.30. Independent samples t-tests and Kruskal-Wallis One-way Analysis of Variance by Ranks tests were performed to test the effect of chronological age (decimal age) and maturational status on morphological, fitness and game performance variables.  
\begin{table}
\begin{tabular}{c c c c} \hline  & \multicolumn{3}{c}{**95\% CI**} \\ \cline{2-5}  & **ICC b** & **Lower Bound** & **Upper Bound** \\ \hline
20-m speed test & 0.937 & 0.921 & 0.949 \\ T-test & 0.946 & 0.929 & 0.959 \\ CMJ heigh & 0.962 & 0.951 & 0.969 \\ CMJ mean power & 0.992 & 0.990 & 0.994 \\ CMJ-S height & 0.958 & 0.947 & 0.966 \\ CMJ-S mean power & 0.980 & 0.975 & 0.984 \\
2-kg MBT test & 0.968 & 0.960 & 0.974 \\ HG rigth hand & 0.980 & 0.975 & 0.984 \\ HG left hand & 0.980 & 0.975 & 0.984 \\ Sit and reach test & 0.922 & 0.903 & 0.938 \\ \hline \end{tabular} b ICC estimates and their 95% confidence intervals were calculated using SPSS statistical package version 22.0 based on a consistency, two-way random-effect model. CI: Confidence interval, CMJ: Countermvement jump, CMJ-S: Countermovement jump with arms swing, ICC: Intraclass correlation, HG: handgrip, MBT: Medicine ball throw.  
\end{table}
Table 1: Intraclass correlation statistics for inter-rater reliability for the physical tests.  
Figure 1: Distribution of self-reported data (Portuguese Health Card) and performed data (cohorts). Frequency of cases by age.