Fig. 2
Effects of OXY administration on rats’ heart rate variability (HRV) during normobaric-normoxia (NN) and hypobaric-hypoxia (HH). (A) Representative power spectral spectrum density during NN and HH after 14 days of Veh and OXY administration. (B) Low-frequency HRV (LFHRV) component. (C) High-frequency HRV (HFHRV) component. (D) LF/HFHRV ratio. N = 6 for each group (repeated measures ANOVA (2 × 2) followed by Holm-Sidak posthoc. *, p < 0.05; **, p < 0.01)