Women at Altitude: Sex-Related Physiological Responses to Exercise in Hypoxia

Abstract

Sex differences in physiological responses to various stressors, including exercise, have been well documented. However, the specific impact of these differences on exposure to hypoxia, both at rest and during exercise, has remained underexplored. Many studies on the physiological responses to hypoxia have either excluded women or included only a limited number without analyzing sex-related differences. To address this gap, this comprehensive review conducted an extensive literature search to examine changes in physiological functions related to oxygen transport and consumption in hypoxic conditions. The review encompasses various aspects, including ventilatory responses, cardiovascular adjustments, hematological alterations, muscle metabolism shifts, and autonomic function modifications. Furthermore, it delves into the influence of sex hormones, which evolve throughout life, encompassing considerations related to the menstrual cycle and menopause. Among these physiological functions, the ventilatory response to exercise emerges as one of the most sex-sensitive factors that may modify reactions to hypoxia. While no significant sex-based differences were observed in cardiac hemodynamic changes during hypoxia, there is evidence of greater vascular reactivity in women, particularly at rest or when combined with exercise. Consequently, a diffusive mechanism appears to be implicated in sex-related variations in responses to hypoxia. Despite well-established sex disparities in hematological parameters, both acute and chronic hematological responses to hypoxia do not seem to differ significantly between sexes. However, it is important to note that these responses are sensitive to fluctuations in sex hormones, and further investigation is needed to elucidate the impact of the menstrual cycle and menopause on physiological responses to hypoxia.

High‐level performances following low altitude training and tapering in warm environments in elite racewalkers

“…The modest increase in Hbmass observed in this study (þ1.7% for absolute Hbmass and þ2.3% for relative Hbmass) (Figure 2) places our findings in line with previous research at altitudes lower than 2000 m, noting that this hypoxic dose could be sufficient in certain, but not all, individuals. Indeed, the large CV% for measurements of both absolute (134%) and relative Hbmass (110%) (Figure 3), and the observation of a positive Hbmass response in most but not all of the cohort (8 out of 10), affirms the typical variability in hematological responses to hypoxic exposure in elite endurance athletes (McLean et al, 2013;Nummela et al, 2021) while there is no evident consensus regarding the influence of sex on Hbmass increase (Raberin et al, 2023). variability in the altitude-induced erythropoietic response (Chapman et al, 1998), such an approach would provide a more detailed understanding of individual responses to an applied hypoxic dose (Soo et al, 2020).…”