The Impact of High-Intensity Exercise in Normobaric Hypoxia on Right Ventricular Function in Trained and Untrained...

Acute exposure to hypoxia affects the cardiovascular system, especially pulmonary circulation and right heart hemodynamics. However, the impact of normobaric hypoxia on the right heart chambers during exercise is still not clear. This study examined whether a single bout of high-intensity exercise to voluntary exhaustion under acute moderate normobaric hypoxia (~3000 m a.s.l.; FiO₂ = 14.4%) induces significant changes in right ventricular (RV) and right atrial (RA) dimensions or RV systolic function compared to normoxia in trained and untrained men. Twenty-four healthy males (12 trained cyclists, 12 untrained) completed randomized trials involving exhaustive exercise under normoxic and hypoxic conditions. Echocardiographic assessments were conducted at rest and post-exercise. While hypoxia was found to reduce total mechanical work, end-exercise heart rate and oxygen saturation in both groups, no differences were observed in the post-exercise RV response between normoxia and hypoxia. Only untrained men showed increased resting RV dimensions and fractional area change (FAC) in hypoxia. Both groups exhibited post-exercise declines in tricuspid annular plane systolic excursion (TAPSE), systolic tissue Doppler velocity (S' wave), and right atrial area (RAA), but no additive effect of hypoxia was observed. These results indicate that acute moderate normobaric hypoxia does not impose additional RV load during maximal exercise in healthy athletes and untrained men. Trial Registration: ClinicalTrials.gov: NCT06896773.