Systolic and Diastolic Functions After a Brief Acute Bout of Mild Exercise in Normobaric Hypoxia

Sara Magnani; Gabriele Mulliri; Silvana Roberto; Fabio Sechi; Giovanna Ghiani; Gianmarco Sainas; Giorgio Nughedu; Romina Vargiu; Pier Paolo Bassareo; Antonio Crisafulli

doi:10.3389/fphys.2021.650696

Systolic and Diastolic Functions After a Brief Acute Bout of Mild Exercise in Normobaric Hypoxia

Front Physiol. 2021 Apr 23:12:650696. doi: 10.3389/fphys.2021.650696. eCollection 2021.

Authors

Sara Magnani^{1

2}, Gabriele Mulliri^{1

2}, Silvana Roberto¹, Fabio Sechi¹, Giovanna Ghiani¹, Gianmarco Sainas¹, Giorgio Nughedu¹, Romina Vargiu³, Pier Paolo Bassareo⁴, Antonio Crisafulli^{1

2}

Affiliations

¹ Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy.
² International PhD in Innovation Sciences and Technologies, University of Cagliari, Cagliari, Italy.
³ Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy.
⁴ University College of Dublin, Mater Misericordiae University Teaching Hospital, Dublin, Ireland.

Abstract

Acute hypoxia (AH) is a challenge to the homeostasis of the cardiovascular system, especially during exercise. Research in this area is scarce. We aimed to ascertain whether echocardiographic, Doppler, and tissue Doppler measures were able to detect changes in systolic and diastolic functions during the recovery after mild exercise in AH. Twelve healthy males (age 33.5 ± 4.8 years) completed a cardiopulmonary test on an electromagnetically braked cycle-ergometer to determine their maximum workload (W_max). On separate days, participants performed randomly assigned two exercise sessions consisting in 3 min pedalling at 30% of W_max: (1) one test was conducted in normoxia (NORMO) and (2) one in normobaric hypoxia with FiO₂ set to 13.5% (HYPO). Hemodynamics were assessed with an echocardiographic system. The main result was that the HYPO session increased parameters related to myocardial contractility such as pre-ejection period and systolic myocardial velocity with respect to the NORMO test. Moreover, the HYPO test enhanced early transmitral filling peak velocities. No effects were detected for left ventricular volumes, as end-diastolic, end-systolic, and stroke volume were similar between the NORMO and the HYPO test. Results of the present investigation support the hypothesis that a brief, mild exercise bout in acute normobaric hypoxia does not impair systolic or diastolic functions. Rather, it appears that stroke volume is well preserved and that systolic and early diastolic functions are enhanced by exercise in hypoxia.

Keywords: blood pressure; cardiac pre-load; echocardiography; myocardial contractility; tissue Doppler.