Exploring the physiological and molecular responses to environmental cross-acclimation

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Intermittent hypoxia training (IHT) in normobaric hypoxia posits a potential solution to allow sea-level individuals the ability to acquire some of the physiological adaptations of altitude without the cost and logistics of relocation. Although IHT is not a recent phenomenon, its use demonstrates equivocal effects on performance in normoxia, with many remaining questions regarding the optimal frequency, intensity, and duration of IHT to prove effective; most recent work demonstrates that a greater hypoxic stimulus with higher intensity, more frequency, and longer durations of IHT sessions posit beneficial physiological effects. Additionally, there is a current gap in our understanding of sex-based differences in response to acute and chronic hypoxia, the underlying mechanisms of response and adaptation specifically related to red blood cell (RBC) function, and the effect hypoxia has on cross-tolerance to heat and vice versa. As well, there is very limited research investigating the effect of intermittent hypoxia exposure on adaptations and performance in Paralympic athletes with varying amounts of functional ability. In this proposal, I aim to bridge the gap between scientific understanding of acute and chronic responses to hypoxia, and acclimation solutions to optimize work capacity and performance outcomes in extreme environments. Furthermore, the long-term goal of my research program is to understand the sex-based physiological and molecular mechanisms of acute and chronic responses to exercise and environmental stress to create interventions that optimize work capacity and performance outcomes. The short-term objectives include: 1) experimentally investigate the sex-based differences and physiological and molecular responses to acute normobaric hypoxia exposure of varying ascents, 2) examine the efficacy, mechanisms, and sex-based differences of short-term hypoxia acclimation (STHA) and its impact on the response to heat stress, and 3) examine the sex-based mechanisms and performance impact of short-term heat acclimation and cross-tolerance to hypoxia. These objectives are inherently linked, but are not necessarily sequentially dependent, ensuring high feasibility and minimal disruption if unanticipated results or delays emerge. This innovative work will fill existing knowledge gaps and markedly advance our understanding of the sex-based physiological and molecular mechanisms of acute and chronic responses to exercise and environmental stress. This knowledge will have broad and significant impact on guiding best practice for use of hypoxia and heat interventions for preparation of athletes, both able-bodied and para-sport, and occupational workers for exposure to extreme environmental conditions.