## 4 Discussion  
In this study, we aimed to determine IL and EL (expressed in relative values) and set-up irregular timing zones (T1: 0-45 min, T2: 45-70 min, T3: 0-70 min, T4: 70-90 min, T5: 45-90 min, and T6: 0-90 min) for elite youth (U17 and U19 age category) soccer matches. Significant differences were noted between the observed match time period for \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & & **T1** & **T2** & **T3** & **T4** & **T5** & **T6** & \multirow{2}{*}{**F**} & \multirow{2}{*}{\(p\)**} & \multirow{2}{*}{\(\eta_{p}\)2**} & \multirow{2}{*}{_Posthoc_} \\ \cline{3-3} \cline{5-10}  & & **0-45** & **45-70** & **0-70** & **70-90** & **45-90** & & & \\ \hline \multirow{3}{*}{HR\({}_{\mathrm{max}}\) (beats.min\({}^{-1}\))} & X & 192.70 & 188.74 & 193.23 & 187.48 & 188.11 & 193.76 & \multirow{3}{*}{57.45} & \multirow{3}{*}{\(<\)0.05} & \multirow{3}{*}{0.47} & a,c,d,f, \\  & SD & 6.57 & 6.58 & 6.40 & 6.61 & 5.97 & 6.05 & & & \\ \hline \multirow{3}{*}{HR\({}_{\mathrm{avg}}\) (beats.min\({}^{-1}\))} & X & 168.41 & 163.85 & 166.62 & 164.53 & 164.19 & 165.58 & \multirow{3}{*}{8.23} & \multirow{3}{*}{\(<\)0.05} & \multirow{3}{*}{0.11} & a,d,f,k,o \\  & SD & 12.38 & 10.06 & 9.36 & 9.92 & 9.12 & 8.73 & & & \\ \hline \multirow{3}{*}{**Time in HR\({}_{\mathrm{Z1}}\) (\%)**} & X & 18.80 & 25.92 & 22.36 & 24.48 & 25.20 & 23.42 & \multirow{3}{*}{4.66} & \multirow{3}{*}{\(<\)0.05} & \multirow{3}{*}{0.07} & a,b,o \\  & SD & 2.01 & 4.65 & 2.80 & 4.62 & 3.95 & 3.29 & & & \\ \hline \multirow{3}{*}{**Time in HR\({}_{\mathrm{Z2}}\) (\%)**} & X & 18.80 & 25.92 & 22.36 & 24.48 & 25.20 & 23.42 & \multirow{3}{*}{6.33} & \multirow{3}{*}{\(<\)0.05} & \multirow{3}{*}{0.09} & a,b,c,d,e,f,o \\  & SD & 16.47 & 17.34 & 15.27 & 17.16 & 15.09 & 14.03 & & & \\ \hline \multirow{3}{*}{**Time in HR\({}_{\mathrm{Z3}}\) (\%)**} & X & 19.29 & 21.93 & 20.62 & 23.56 & 22.75 & 22.09 & \multirow{3}{*}{5.28} & \multirow{3}{*}{\(<\)0.05} & \multirow{3}{*}{0.08} & \multirow{3}{*}{} \\  & SD & 10.18 & 9.43 & 8.43 & 9.96 & 8.25 & 7.65 & & & \\ \hline \multirow{3}{*}{**Time in HR\({}_{\mathrm{Z4}}\) (\%)**} & X & 22.79 & 24.97 & 23.89 & 28.02 & 26.50 & 25.96 & \multirow{3}{*}{5.03} & \multirow{3}{*}{0.07} & \\  & SD & 10.38 & 11.67 & 9.48 & 17.17 & 13.28 & 12.07 & & & \\ \hline \multirow{3}{*}{**Time in HR\({}_{\mathrm{Z5}}\) (\%)**} & X & 34.53 & 19.57 & 27.05 & 17.85 & 18.71 & 22.45 & \multirow{3}{*}{26.82} & \multirow{3}{*}{\(<\)0.05} & \multirow{3}{*}{0.29} & a,b,c,d,e, \\  & SD & 25.63 & 17.40 & 19.47 & 14.89 & 14.57 & 14.86 & & \\ \hline \hline \end{tabular} Note: HR\({}_{\mathrm{max}}\): maximum heart rate, (beats.min\({}^{-1}\)), HR\({}_{\mathrm{avg}}\): average heart rate (beats.min\({}^{-1}\)), time spent in different intensities zones (Z1-Z5), time in HR\({}_{\mathrm{2}}\): steady state intensity (%), time in HR\({}_{\mathrm{2}}\): low intensity (%), time in HR\({}_{\mathrm{2}}\): aerobic intensity (%), time in HR\({}_{\mathrm{4}}\): submaximal intensity (%), time in HR\({}_{\mathrm{2}}\): maximum intensity (%); a—difference between T1 and T2; b—significant difference between T1 and T3; c—significant difference between T1 and T4; d—significant difference between T2 and T3; g—significant difference between T1 and T6; f—significant difference between T2 and T3; g—significant difference between T2 and T4; b—significant difference between T3 and T4; k—significant difference between T3 and T5; l—significant difference between T3 and T6; f—significant difference between T4 and T5; n—significant difference between T4 and T6; o—significant difference between T5 and T6.  
\end{table} 
Table 2: Comparison of internal load parameters of the different match time periods. all EL and IL (Table 1, Table 2). Players reached higher \(\text{TDC}_{\text{rel}}\) by 6.6% (123.09 \(\pm\) 9.48 vs. 115.03 m.min\({}^{-1}\)) in the first half than in the second half.