Arterial haemoglobin oxygen saturation and power output are maintained at peak oxygen consumption in upper compared to lower body exercise in normobaric hypoxia

Purpose: To examine the effect of reduced FIO2 and the magnitude of reduction in peak, peak power output (PPO) and arterial haemoglobin oxygen saturation (SpO2) in upper compared to lower body exercise. Methods: Nine healthy able-bodied male participants (age mean 22 ± 2 years) undertook three upper and three lower body discontinuous (30 sec intervals) incremental exercise tests to volitional exhaustion (UBX; LBX) whilst breathing either normoxia (N) or normobaric hypoxia (H1 and H2); FIO2s ≈ 0.21, 0.15 and 0.13 respectively. Data were examined using general linear model analysis of variance. Results: UBX peak was 71 ± 10 and 76 ± 8% whereas PPO was 50 ± 5 and 55 ± 3% of that in LBX at H1 and H2 respectively; demonstrating that PPO were maintained in UBX relative to LBX in H2. Correspondingly SpO2 was 79 ± 4% in UBX versus 73 ± 4% in LBX at H2 compared to 85 ± 5% in UBX versus 83 ± 4% in LBX at H1. Conclusion: UBX same manner as LBX with reduced FIO2. This may be explained by the smaller reduction in SpO2 observed during UBX compared to LBX.