Menstrual cycle does not impact the hypoxic ventilatory response and acute mountain sickness prediction

Abstract

The relationship between the variations in ovarian hormones (i.e., estrogens and progesterone) and the hypoxic ventilatory response (HVR) remains unclear. HVR is a key adaptive mechanism to high altitude and has been proposed as a predictor for acute mountain sickness (AMS). This study aimed to explore the effects of hormonal changes across the menstrual cycle on HVR. Additionally, it assessed the predictive capacity of HVR for AMS and examined whether a particular menstrual phase could enhance its predictive accuracy. Thirteen eumenorrheic women performed a pure nitrogen breathing test near sea level, measuring HVR and cerebral oxygenation in early follicular, late follicular, and mid-luteal phases. Oxidative stress and ovarian hormone levels were also measured. AMS symptoms were evaluated after spending 14 h, including one overnight, at an altitude of 3,375 m. No differences in HVR, ventilation, peripheral oxygen saturation, or cerebral oxygenation were observed between the three menstrual cycle phases. Moreover, these parameters and the oxidative stress markers did not differ between the women with or without AMS (31% vs 69%), regardless of the menstrual cycle phase. In conclusion, ventilatory responses and cerebral oxygenation in normobaric hypoxia were consistent across the menstrual cycle. Furthermore, these parameters did not differentiate women with or without AMS.

Keywords: [Formula: see text]; Chemosensitivity; Estradiol; Female; Premenopausal; SpO2.

Fig. 1

Study design.

Fig. 2

Measurements during the pure nitrogen breathing test in a typical participant. Panel (A) illustrates ventilation and peripheral oxygen saturation (SpO₂) for each nitrogen exposure, with the number of breaths indicated within squares. The peak values are utilized for calculating the hypoxic ventilatory response (HVR) in Panel (B). Prefrontal cerebral oxygenation, indicated by total saturation index (TSI) and deoxyhemoglobin (HHb), is depicted in Panel (C), while Panel D displays the calculation of their slope and amplitude in a representative nitrogen exposure.

Fig. 3

Ovarian hormones at early follicular (Fol1), late follicular (Fol2), and mid-luteal (Lut3) phases of the menstrual cycle. *, significantly higher than Fol1 and Fol2. Each symbol represents mean ± SEM.

Fig. 4

Hypoxic ventilatory response (HVR) at early follicular (Fol1), late follicular (Fol2), and mid-luteal (Lut3) phases of the menstrual cycle. Values are mean ± SD.