Antioxid Redox Signal. 2022 Feb 01.
SIGNIFICANCE: Oxygen is indispensable for aerobic life but its utilization exposes cells and tissues to oxidative stress; thus, tight regulation of cellular, tissue and systemic oxygen concentrations is crucial. Here, we review the current understanding of how the human organism (mal-)adapts to low (hypoxia) and high (hyperoxia) oxygen levels and how these adaptations may be harnessed as therapeutic or performance enhancing strategies at the systemic level. Recent Advances: Hyperbaric oxygen therapy is already a cornerstone of modern medicine and the application of mild hypoxia, i.e., hypoxia conditioning, to strengthen the resilience of organs or the whole body to severe hypoxic insults is important preparation for high-altitude sojourns or to protect the cardiovascular system from hypoxic/ischemic damage. Many other applications of adaptations to hypo- and/or hyperoxia are only just emerging. Hypoxia conditioning - sometimes in combination with hyperoxic interventions - is gaining traction for the treatment of chronic diseases, including numerous neurological disorders, and for performance enhancement.
CRITICAL ISSUES: The dose- and intensity-dependent effects of varying oxygen concentrations render hypoxia- and/or hyperoxia-based interventions potentially highly beneficial, yet hazardous, although the risks vs. benefits are as yet ill-defined.
FUTURE DIRECTIONS: The field of low and high oxygen conditioning is expanding rapidly and novel applications are increasingly recognized, e.g., the modulation of aging processes, mood disorders or metabolic diseases. To advance hypoxia/hyperoxia conditioning to clinical applications, more research on the effects of the intensity, duration and frequency of altered oxygen concentrations, as well as on individual vulnerabilities to such interventions, is paramount.