*3.5. Erythrocyte O2 Release Capacity in Normal Conditions*

As Figure 5A,F shows, oxygen was absorbed into the cell when isolated erythrocytes were added to the normoxia chamber, which produced a negative oxygen pressure difference (O2 pressure-diff). Furthermore, this oxygen was released at lactate acid concentrations of 1 and 4 mM. After an acute GXT, the magnitudes of oxygen absorption and release were diminished (Figure 5A,C) and coupled with a reduced flux velocity (Figure 5D,F). Following the interventions, both training groups exhibited a diminished O2 pressure-diff and velocity in 0 and 1 mM lactate acid conditions at rest and even after the GXT. However, both CCT and ECT induced maintenance of these parameters at resting levels in the 4 mM lactate acid condition (Figure 5C,F).

**Figure 5.** Measurement of oxygen release capacity of erythrocytes among three groups in normoxia and hypoxia conditions. Levels of O2 pressure-diff in normoxia condition: (**A**) at 0 mM [lac], (**B**) at 1 mM [lac], and (**C**) at 4 mM [lac]; oxygen flux per volume in normoxia condition: (**D**) at 0 mM [lac], (**E**) at 1 mM [lac], and (**F**) at 4 mM [lac]; levels of O2 pressure-diff in hypoxia condition: (**G**) at 0 mM [lac], (**H**) at 1 mM [lac], and (**I**) at 4 mM [lac]; oxygen flux per volume in hypoxia condition: (**J**) at 0 mM [lac], (**K**) at 1 mM [lac], and (**L**) at 4 mM [lac]; Pre, pre-intervention; Post, post-intervention; R, at rest; M, immediately after a GXT; \* *p* < 0.05, R vs. M; † *p* < 0.05, Pre vs. Post. Values were mean ± SEM.
