## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Variable**} & \multirow{2}{*}{**Group**} & \multirow{2}{*}{**Pre**} & \multirow{2}{*}{**Post**} & \multirow{2}{*}{**Effect: Group**} & \multirow{2}{*}{**Effect: Time**} & \multirow{2}{*}{**Interaction**} & \multirow{2}{*}{**Post Hoc**} & \multirow{2}{*}{**Pre vs. Post**} \\  & & & & **F** & **F** & **F** & **Pre vs. Post** \\  & & & & **\(\mathbf{p^{2}}\)** & \(\mathbf{p^{2}}\)** & \(\mathbf{np^{2}}\)** & \(\mathbf{np^{2}}\)** \\ \hline \multirow{3}{*}{\begin{tabular}{c} P\({}_{\text{VT2}}\) \\ (W) \\ \end{tabular} } & ctrl & 166.2 \(\pm\) 20.2 & 163.9 \(\pm\) 37.4 & 8.02 & 6.44 & 3.23 & 0.99 & 0.08 \\ \cline{2-9}  & NT & 162.5 \(\pm\) 21.1 & 173.4 \(\pm\) 26.5 & 0.001 & 0.01 & 0.04 & 0.72 & 0.46 \\ \cline{2-9}  & IHT & 183.8 \(\pm\) 29.2 & 209.2 \(\pm\) 36.1 & 0.26 & 0.12 & 0.13 & 0.02 & 0.78 \\ \hline \multirow{3}{*}{\begin{tabular}{c} rel\({}_{\text{PVT}}\) \\ (W/kg) \\ \end{tabular} } & ctrl & 2.23 \(\pm\) 0.39 & 2.20 \(\pm\) 0.54 & 2.89 & 6.00 & 3.19 & 0.99 & 0.06 \\ \cline{2-9}  & NT & 2.14 \(\pm\) 0.37 & 2.27 \(\pm\) 0.37 & 0.06 & 0.02 & 0.05 & 0.76 & 0.35 \\ \cline{2-9}  & IHT & 2.34 \(\pm\) 0.46 & 2.65 \(\pm\) 0.44 & 0.11 & 0.12 & 0.12 & 0.02 & 0.69 \\ \hline \multirow{3}{*}{\begin{tabular}{c} \%Pmax \\ \end{tabular} } & ctrl & 61.4 \(\pm\) 7.92 & 57.9 \(\pm\) 12.8 & 4.11 & 0.10 & 1.24 & 0.67 & - \\ \cline{2-9}  & NT & 57.4 \(\pm\) 8.66 & 58.5 \(\pm\) 7.92 & 0.02 & 0.74 & 0.29 & 0.99 & - \\ \cline{2-9}  & IHT & 64.5 \(\pm\) 6.87 & 65.5 \(\pm\) 6.55 & 0.15 & 0.002 & 0.05 & 0.99 & - \\ \hline \multirow{3}{*}{\begin{tabular}{c} HR\({}_{\text{VT2}}\) \\ (ppm) \\ \end{tabular} } & ctrl & 153 \(\pm\) 17 & 144 \(\pm\) 18 & 0.95 & 0.48 & 6.51 & 0.02 & - \\ \cline{2-9}  & NT & 148 \(\pm\) 13 & 148 \(\pm\) 16 & 0.39 & 0.49 & 0.003 & 0.49 & - \\ \cline{2-9}  & IHT & 151 \(\pm\) 7 & 157 \(\pm\) 8 & 0.04 & 0.01 & 0.22 & 0.45 & - \\ \hline \multirow{3}{*}{\
\begin{tabular}{c} \%HRmax \\ \end{tabular} } & ctrl & 83.5 \(\pm\) 6.3 & 79.2 \(\pm\) 8.2 & 2.24 & 1.53 & 4.31 & 0.03 & - \\ \cline{2-9}  & NT & 80.5 \(\pm\) 6.1 & 80.4 \(\pm\) 6.0 & 0.11 & 0.22 & 0.01 & 0.99 & - \\ \cline{2-9}  & IHT & 83.5 \(\pm\) 3.8 & 54.9 \(\pm\) 3.9 & 0.09 & 0.03 & 0.16 & 0.92 & - \\ \cline{2-9}  & ctrl & 2.12 \(\pm\) 0.22 & 2.13 \(\pm\) 0.35 & 8.03 & 11.73 & 2.96 & 0.99 & 0.04 \\ \cline{2-9}  & NT & 2.15 \(\pm\) 0.28 & 2.34 \(\pm\) 0.55 & 0.001 & 0.001 & 0.06 & 0.27 & 0.46 \\ \cline{2-9}  & IHT & 2.38 \(\pm\) 0.35 & 2.68 \(\pm\) 0.43 & 0.25 & 0.20 & 0.11 & 0.01 & 0.77 \\ \hline \multirow{3}{*}{
\begin{tabular}{c} \%VO2 max \\ \end{tabular} } & ctrl & 64.1 \(\pm\) 8.1 & 63.6 \(\pm\) 11.1 & 3.09 & 1.35 & 0.83 & - & - \\ \cline{2-9}  & NT & 61.2 \(\pm\) 9.9 & 62.7 \(\pm\) 8.4 & 0.05 & 0.25 & 0.44 & - & - \\ \cline{2-9}  & IHT & 66.5 \(\pm\) 5.9 & 69.8 \(\pm\) 4.4 & 0.11 & 0.03 & 0.03 & - & - \\ \hline \hline \end{tabular}  
* P: power output, VT2: second ventilatory threshold; HR: heart rate; VO2: oxygen uptake; ctrl: control group; NT: normoxia training; IHT: intermittent hypoxia training.  
\end{table} 
Table 3: Effects of interval training performed in normoxia and hypoxia on parameters noted at the second ventilatory threshold (data are presented as mean \(\pm\) SD). training in normoxia-maximal power output and power output at VT2 and VO2 at VT2 were improved after training. In this study, IHT was ineffective in improving VO2 max, which is consistent with what has been reported in previous studies [28,29] in which a non-significant increase in VO2 max was observed, and in contrast to data presented by [PERSON] et al. [30], who showed significant improvement in VO2 max after brief IHT. The lack of improvement in maximal oxygen uptake indicates that the hypoxic stimulation used in this study ('hypoxic dose'), may have been too weak to improve hematological parameters and the efficiency of oxygen delivery to working muscles. The IHT protocol also may be insufficient to accelerate erythropoiesis [28].