## 2 Methods
#### Data Analysis  
Each lower limb was analyzed independently since the joint range of motion, arch height, plantar pressure distribution, and other morphofunctional parameters can differ \begin{table}
\begin{tabular}{p{113.8 pt} p{71.1 pt} p{71.1 pt} p{71.1 pt}} \hline \hline
**Variable** & **Measurement Unit** & **Group Junior (Media \(\pm\) DE)** & **Group Absolut (Media \(\pm\) DE)** \\ \hline Age & Years & 17.0 \(\pm\) 0.8 & 21.1 \(\pm\) 1.5 \\ \hline Weight & kg & 70.5 \(\pm\) 5.4 & 73.8 \(\pm\) 6.2 \\ \hline Height & cm & 175.2 \(\pm\) 6.1 & 178.4 \(\pm\) 5.8 \\ \hline Ankle Dorsiflexion (Knee extended) & Degrees (\({}^{\circ}\)) & 10.5 \(\pm\) 2.1 & 8.7 \(\pm\) 1.9 \\ \hline Ankle Dorsiflexion (Knee flexion) & Degrees (\({}^{\circ}\)) & 12.3 \(\pm\) 2.5 & 10.1 \(\pm\) 2.3 \\ \hline Rearfoot Mobility & Degrees (\({}^{\circ}\)) & 10.1 \(\pm\) 2.3 & 7.5 \(\pm\) 1.6 \\ \hline Dorsal Flexion of the 1 st MTP & Degrees (\({}^{\circ}\)) & 50.4 \(\pm\) 5.2 & 47.2 \(\pm\) 4.8 \\ \hline Firs Ray Mobility & mm & 6.5 \(\pm\) 1.3 & 5.2 \(\pm\) 1.5 \\ \hline Foot Posture (FPI) & Scale (\(-12\) to \(+12\)) & 4.0 \(\pm\) 2.0 & 3.0 \(\pm\) 2.0 \\ \hline Arch Eight & Degrees (Clarke’s angle) & 38.2 \(\pm\) 3.5 & 36.8 \(\pm\) 4.1 \\ \hline Plantar Pressure & kPa & 250.4 \(\pm\) 30.2 & 270.6 \(\pm\) 28.9 \\ \hline Pain Presence (NPRS) & Scale (0–10) & 3.8 \(\pm\) 1.2 & 4.1 \(\pm\) 1.3 \\ \hline Pain Location & Category & Triceps surae, plantar muscles & Triceps surae, plantar muscles \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Variables and Units of Measurement. between the right and left sides of the same individual. Considering each limb separately allows for a more detailed and accurate assessment of the characteristics under study. For the descriptive analysis, the absolute frequency (N), relative frequency (%), mean values, standard deviation (SD), median and interquartile range (IQR) were calculated. For quantitative variables, normality was evaluated using the Shapiro-Wilk test. To determine whether there were differences between the JR and AB groups, the _t_-test for independent samples was applied if the variables were normal, or the Mann-Whitney U test if they were not. In the case of qualitative variables, the chi-square test was used. A two-stage cluster analysis was carried out using the silhouette measure of cohesion and separation coefficient, with the aim of finding out the values of the variables that differentiate the JR and AB groups at the global level. To determine whether foot type, classified according to the Foot Posture Index (FPI) and Clarke's angle, influenced the 50 m swimming time, a one-way ANOVA test was conducted. A confidence level of 95% was taken into account so that the experimental _p_-value was compared with a significance level of 5%. To assess intra-rater reliability, a subgroup of 12 randomly selected participants underwent repeated measurements 10 to 15 days after the initial assessment. The intraclass correlation coefficient (ICC) was calculated to evaluate the reliability of the measurements. Statistical analysis was performed using the IBM SPSS Statistics 27 statistical package. A post hoc power analysis was conducted by calculating the sample size, and the following results were obtained. The variable ankle dorsiflexion with a flexed knee was taken as a reference, as it was the significant variable with the smallest effect size in this study. The sample size for the comparison of two means was calculated. The formula applied is:  
\[n=\frac{2s^{2}\Big{(}z_{\frac{\beta}{2}}+z_{\beta}\Big{)}^{2}}{d^{2}}\]  
\(s\). Standard deviation estimation based on this study. A mean value of 3.8 standard deviations was obtained. \(\alpha\). Type I error. An a priori value of \(\alpha\) = 0.05 was used. \(\beta\). Type II error. \(1-\beta\) is the power, which is the value to be calculated. \(d\). Minimum detectable difference. In this study, the mean difference was 2.7.