Mitophagy Markers and Mitochondrial Oxidative Phosphorylation in Peripheral Blood Mononuclear Cells after Endurance Exercise under Normobaric Hypoxia: A Pilot study

Hypoxia and endurance exercise (EE) independently induce cellular stress, affecting mitophagy and mitochondrial function. Their combined effect remains poorly understood in human peripheral blood mononuclear cells (PBMCs). This exploratory pilot study aimed to generate hypotheses regarding the acute effects of EE under normobaric hypoxia (NH) on markers of mitochondrial oxidative phosphorylation (OXPHOS) and mitophagy in PBMCs. Methods: Four men performed an acute bout of EE under normoxia and NH in a crossover design. Physiological parameters and PBMCs were collected before and after exercise. OXPHOS proteins and parkin were quantified in PBMCs. In addition, basal oxygen consumption rate (OCR) was assessed in PBMCs. Results:In PBMCs, NH tended to reduce Complex I (p = 0.07), whereas EE increased Complex II (p = 0.04). NH decreased parkin abundance (p = 0.01), while EE tended to increase it (p = 0.07), with no significant condition-by-intervention interaction (p = 0.56). Conclusion: This pilot study suggests differential modulation of parkin in PBMCs by EE and NH, without changes in basal OCR. The absence of a significant EE × NH interaction on parkin in this small sample supports the need for further investigation in larger cohorts.