# The Effects of Loaded Plyometries and Short Sprints in U19 Male Soccer Players in Tunisia
## 3 Results
### Effect of Training on Jump and Sprint Performance  
For vertical and horizontal jump performance, intervention effects (group \(\times\) time interaction) were significant for all parameters and ranged from \(\eta_{\text{p}}\)\({}^{2}\) = 0.94 (5 JT) to \(\eta_{\text{p}}\)\({}^{2}\) = 0.99 (S). The interaction effects for the sprint parameters were of a similar magnitude (from \(\eta_{\text{p}}\)\({}^{2}\) = 0.94 (10 m sprint) to \(\eta_{\text{p}}\)\({}^{2}\) = 0.95 (30 m sprint) (Table 4)).  
The effect sizes (d) for EG were consistently higher than for CG. The improvements of performance in EG ranged from d = 1.69 (5 JT) to d = 2.56 (30 m sprint), whereas the effect  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**EG (n = 18)**} & \multicolumn{3}{c}{**CG (n = 16)**} & \multicolumn{3}{c}{**Variance Analysis \(p\) (\(\eta_{\text{p}}\)\({}^{2}\))**} \\ \cline{2-9}  & **Test** & **Retest** & **d** & **Test** & **Retest** & **d** & **Group** & **Time** & **Group \(\times\) Time** \\ \hline \multicolumn{9}{c}{Vertical jump} \\ S[ (cm)] (cm) & 29.6 \(\pm\) 3.19 & 35.7 \(\pm\) 3.28 & 1.89 & 29.7 \(\pm\) 2.48 & 30.7 \(\pm\) 2.45 & 0.41 & 0.020 (0.16) & \textless{}0.001 (1.00) & \textless{}0.001 (0.99) \\ CMJ[A (cm)] (cm) & 36.0 \(\pm\) 3.83 & 43.4 \(\pm\) 4.05 & 1.88 & 35.5 \(\pm\) 2.33 & 36.6 \(\pm\) 2.28 & 0.48 & 0.003 (0.25) & \textless{}0.001 (0.99) & \textless{}0.001 (0.98) \\ \hline \multicolumn{9}{c}{Horizontal jump} \\
10 m (s) & 11.3 \(\pm\) 0.87 & 12.7 \(\pm\) 0.79 & 1.69 & 11.3 \(\pm\) 0.49 & 11.7 \(\pm\) 0.40 & 0.90 & 0.029 (0.14) & \textless{}0.001 (0.98) & \textless{}0.001 (0.94) \\ \hline \multicolumn{9}{c}{Sprini} \\
10 m (s) & 1.70 \(\pm\) 0.12 & 1.50 \(\pm\) 0.10 & 1.82 & 1.72 \(\pm\) 0.04 & 1.68 \(\pm\) 0.04 & 1.00 & 0.001 (0.28) & \textless{}0.001 (0.97) & \textless{}0.001 (0.94) \\
30 m (s) & 4.42 \(\pm\) 0.18 & 4.01 \(\pm\) 0.14 & 2.56 & 4.43 \(\pm\) 0.15 & 4.36 \(\pm\) 0.15 & 0.44 & 0.001 (0.28) & \textless{}0.001 (0.98) & \textless{}0.001 (0.95) \\ \hline \end{tabular}
\end{table}
Table 4: Jump and sprint test performances depending on groups (EG vs. CG) before and after 8-week intervention. Meaningful effects (criteria: \(p\) < 0.05 and \(\eta_{\text{p}}\)\({}^{2}\) > 0.15 and d > 0.80) are highlighted in bold.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **ICC (95\% CI)** & **CV (95\%CI) [\%]** \\ \hline \multicolumn{4}{c}{_Sprint times_} \\
10 m (s) & 0.95 (0.92–0.98) & 1.7 (1.3–2.2) \\
30 m (s) & 0.94 (0.91–0.97) & 1.8 (1.5–2.3) \\ \hline \multicolumn{4}{c}{_Change of direction test_} \\ S90\({}^{\circ}\) (s) & 0.92 (0.90–0.95) & 1.5 (1.2–1.9) \\ SBF (s) & 0.90 (0.88–0.94) & 1.8 (1.5–2.2) \\ \hline \multicolumn{4}{c}{_Vertical jump_} \\ SJ (cm) & 0.95 (0.91–0.98) & 1.9 (1.5–2.3) \\ CMJ (cm) & 0.94 (0.91–0.97) & 2.1 (1.8–2.6) \\ \hline \multicolumn{4}{c}{_Horizontal jump_} \\
5 JT (m) & 0.86 (0.82–0.90) & 3.9 (3.7–4.3) \\ \hline \multicolumn{4}{c}{_Y-balance test_} \\ Right support leg \\ Anterior direction (cm) & 0.98 (0.92–0.99) & 4.3 (4.0–4.8) \\ Posteromedial direction (cm) & 0.97 (0.91–0.99) & 4.4 (4.0–4.7) \\ Posterolateral direction (cm) & 0.95 (0.92–0.98) & 4.7 (4.2–5.1) \\ Left support leg \\ Anterior direction (cm) & 0.97 (0.93–0.99) & 4.5 (4.1–5.0) \\ Posteromedial direction (cm) & 0.97 (0.92–0.99) & 4.5 (4.0–4.8) \\ Posterolateral direction (cm) & 0.94 (0.90–0.98) & 4.8 (4.4–5.3) \\ \hline \end{tabular}
\end{table}
Table 3: Interclass correlation coefficient (ICC, 95% confidence intervals (95% CI)) and coefficient of variation (CV) showing excellent reliability for all performance parameters.  
sizes for CG were markedly lower (d\({}_{\rm range}\): 0.41 to 1.00). No difference between groups was observed for 5 JT (\(\eta_{\rm p}\)\({}^{2}\) = 0.14).