## 3 Results  
Table 1 shows the descriptive results of the 8 \(\times\) 10 m shuttle test divided by gender.  
Table 2 illustrates the outcomes of the 8 \(\times\) 10 m shuttle test for each group across both genders. The results indicate a significantly diminished agility performance in both male and female groups when comparing various time periods (\(p<0.05\)). Among boys, there was a notable decline in agility capacity, becoming significant from the 2007-2011 period onwards (F\({}_{(3,839)}\) = 392, \(p<0.001\), \(\eta_{\mathrm{p}}\)\({}^{2}\) = 0.584). Group 1 (2002-2006) exhibited a superior performance (22.76 \(\pm\) 1.84) compared to Group 3 (2012-2016) and Group 4 (2017-2022) (at 27.57 \(\pm\) 2.38, \(p<0.001\), \(d\) = 2.48 (2.25-2.70) and 27.42 \(\pm\) 2.53, \(p<0.001\), \(d\) = 2.36 (2.14-2.59), respectively). Similarly, Group 2 (2007-2011) also demonstrated higher performance (22.97 \(\pm\) 1.73) in contrast to Group 3 (2012-2016) and Group 4 (2017-2022) (\(p<0.001\), \(d\) = 2.37 (2.15-2.60) and \(p<0.001\), \(d\) = 2.26 (2.03-2.48), respectively), indicating a decline in results (Figure 1).  
The girls' trend showed a similar pattern. There was significantly lower agility over time (F\({}_{(3,593)}\) = 414, \(p<0.001\), \(\eta_{\mathrm{p}}\)\({}^{2}\) = 0.677). Girls reported the highest performance in the 2002-2006 Group (23.79 \(\pm\) 1.53). Group 1 (2002-2006) exhibited a superior performance (23.79 \(\pm\) 1.53) compared to Group 2 (2007-2011), Group 3 (2012-2016), and Group 4 (2017-2022) (at 24.54 \(\pm\) 1.46, \(p\) = 0.009, \(d\) = 0.39 (0.15-0.63), 29.52 \(\pm\) 2.16, \(p<0.001\), \(d\) = 3.09 (2.80-3.38), and 29.57 \(\pm\) 2.12, \(p<0.001\), \(d\) = 3.09 (2.80-3.38), respectively). Similarly, Group 2 (2007-2011) also demonstrated a higher performance in contrast to Group 3 (2012-2016) and Group 4 (2017-2022) (\(p<0.001\), \(d\) = 2.70 (2.42-2.96) and \(p<0.001\), \(d\) = 2.71 (2.43-2.97), respectively), indicating a decline in results (Figure 2).  
\begin{table}
\begin{tabular}{l l l l l} \hline  & **Boys (\(n\) = 842)** & **Girls (\(n\) = 596)** & **Total (\(n\) = 1439)** & **ICC (95\% CI)** \\ \hline
8 \(\times\) 10 m shuttle run test (s) & 25.42 \(\pm\) 3.11 & 27.14 \(\pm\) 3.26 & 26.16 \(\pm\) 3.28 & 0.86 (0.81-0.90) \\ \hline \end{tabular}  
* ICC—intraclass correlation coefficient; CI—confidence intervals; m—meters; s—seconds.  
\end{table}
Table 1: Descriptive analysis of the 8 \(\times\) 10 m shuttle test results categorized by gender. Data are presented as mean \(\pm\) SD.  
\begin{table}
\begin{tabular}{l l l l l} \hline  & **Group 1:** & **Group 2:** & **Group 3:** & **Group 4:** \\  & **2002–2006** & **2007–2011** & **2012–2016** & **2017–2022** \\ \hline Boys & 22.76 \(\pm\) 1.84 & 22.97 \(\pm\) 1.73 & 27.57 \(\pm\) 2.38 *+ & 27.42 \(\pm\) 2.53 *+ \\ Girls & 23.79 \(\pm\) 1.53 & 24.54 \(\pm\) 1.46 \$ & 29.52 \(\pm\) 2.16 \$ & 29.57 \(\pm\) 2.12 \$ \\ \hline \end{tabular}  
* \(\star\)—statistically different to Group 1; \(\ddagger\)—statistically different to Group 2; \(\ddagger\)—statistically different to Group 1; \(\ddagger\)—statistically different to Group 2.  
\end{table}
Table 2: Descriptive analysis of results in 8 \(\times\) 10 m shuttle run test over a 20-year period. The data are shown as mean \(\pm\) SD.  
Figure 1: Comparison of \(8\times 10\) m shuttle run test results between the boys’ groups.  
Figure 2: Comparison of \(8\times 10\) m shuttle run test results between the girls’ groups.