Accelerated Red Blood Cell Turnover Following Extreme Mountain Ultramarathon?

Introduction: Mountain ultramarathon induces extreme physiological stress for the human body. For instance, a decrease in total hemoglobin mass (Hbmass) due to severe hemolysis is historically suspected. Nevertheless, hematological changes following a 330-km mountain ultramarathon have to date never been investigated.

Effect of menstrual cycle phase on physiological responses in healthy women at rest and during submaximal exercise at high altitude.

As more women engage in high-altitude activities, understanding how ovarian hormone fluctuations affect their cardiorespiratory system is essential for optimizing acclimatization to these environments. This study investigates the effects of menstrual cycle (MC) phases on physiological responses at rest, during and after submaximal exercise, at high-altitude (barometric pressure 509 ± 6 mmHg; partial pressure of inspired oxygen 96 ± 1 mmHg; ambient temperature 21 ± 2 °C and relative humidity 27 ± 4%) in 16 eumenorrheic women. Gas exchange, hemodynamic responses, heart rate variability and heart rate recovery (HRR) were monitored at low altitude, and then at 3375 m on the Mont Blanc (following nocturnal exposure) during both the early-follicular (EF) and mid-luteal (ML) phases.