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. 2022 Apr 10;19(8):4558.
doi: 10.3390/ijerph19084558.

Acute Exercise with Moderate Hypoxia Reduces Arterial Oxygen Saturation and Cerebral Oxygenation without Affecting Hemodynamics in Physically Active Males

Gabriele Mulliri  1   2 , Sara Magnani  1   2 , Silvana Roberto  1 , Giovanna Ghiani  1 , Fabio Sechi  1 , Massimo Fanni  1 , Elisabetta Marini  3 , Silvia Stagi  3 , Ylenia Lai  4 , Andrea Rinaldi  4 , Raffaella Isola  4 , Romina Vargiu  4 , Marty D Spranger  5 , Antonio Crisafulli  1   2
Affiliations

Acute Exercise with Moderate Hypoxia Reduces Arterial Oxygen Saturation and Cerebral Oxygenation without Affecting Hemodynamics in Physically Active Males

Gabriele Mulliri et al. Int J Environ Res Public Health. .

Abstract

Hemodynamic changes during exercise in acute hypoxia (AH) have not been completely elucidated. The present study aimed to investigate hemodynamics during an acute bout of mild, dynamic exercise during moderate normobaric AH. Twenty-two physically active, healthy males (average age; range 23-40 years) completed a cardiopulmonary test on a cycle ergometer to determine their maximum workload (Wmax). On separate days, participants performed two randomly assigned exercise tests (three minutes pedaling at 30% of Wmax): (1) during normoxia (NORMO), and (2) during normobaric AH at 13.5% inspired oxygen (HYPO). Hemodynamics were assessed with impedance cardiography, and peripheral arterial oxygen saturation (SatO2) and cerebral oxygenation (Cox) were measured by near-infrared spectroscopy. Hemodynamic responses (heart rate, stroke volume, cardiac output, mean arterial blood pressure, ventricular emptying rate, and ventricular filling rate) were not any different between NORMO and HYPO. However, the HYPO test significantly reduced both SatO2 (96.6 ± 3.3 vs. 83.0 ± 4.5%) and Cox (71.0 ± 6.6 vs. 62.8 ± 7.4 A.U.) when compared to the NORMO test. We conclude that an acute bout of mild exercise during acute moderate normobaric hypoxia does not induce significant changes in hemodynamics, although it can cause significant reductions in SatO2 and Cox.

Keywords: blood pressure; cardiac output; stroke volume; ventricular emptying rate; ventricular filling rate.

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Conflict of interest statement

The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Schematic representation of the experimental protocol.
Figure 2
Figure 2
Changes in the level of peripheral blood O2 saturation (SatO2, (panel A) during the sessions of exercise (Exe) in normoxia (NORMO) and in normobaric hypoxia with a FiO2 of 13.5% (HYPO). Panel B shows changes in regional cerebral oxygenation (Cox) during the same tests. Values are mean with 95% confidence interval. N = 22. * = p < 0.05 between NORMO and HYPO at the same time point. † = p < 0.05 vs. rest, 3 min of recovery (Rec 3), and 6 min of recovery (Rec 6) of the same test.
Figure 3
Figure 3
Changes in the level of heart rate (HR, panel A), stroke volume (SV, panel B), and cardiac output (CO, panel C) during the sessions of exercise in normoxia (NORMO) and in normobaric hypoxia with a FiO2 of 13.5% (HYPO). Values are mean with 95% confidence interval. N = 22.
Figure 4
Figure 4
Changes in the level of pre-ejection period (PEP, panel A), ventricular ejection time (VET, panel B), and diastolic time (DT, panel C) during the sessions of exercise in normoxia (NORMO) and in normobaric hypoxia with a FiO2 of 13.5% (HYPO). Values are mean with 95% confidence interval. N = 22.
Figure 5
Figure 5
Changes in the level of ventricular filling rate (VFR, panel A), ventricular emptying rate (VER, panel B), mean arterial pressure (MAP, panel C), and systemic vascular resistance (SVR, panel D) during the sessions of exercise in normoxia (NORMO) and in normobaric hypoxia with a FiO2 of 13.5% (HYPO). Values are mean with 95% confidence interval. N = 22.
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