FEMALES PRESERVE MORE WORK CAPACITY THAN MALES WHEN EXPOSED TO NORMOBARIC HYPOXIA
Jacobs, K. A., Stoutenberg, M., Kressler, J., Roos, B., & Friedlander, A. L. (2009). Trained women demonstrate greater preservation of peak exercise capacity during acute hypoxia than trained men. ACSM 56th Annual Meeting, Seattle, Washington. Presentation number 2121.
This study investigated the effects of acute normobaric hypoxia on cardiovascular hemodynamics at rest and during maximal exercise in endurance trained male (N = 20) and female (N = 15) cyclists and triathletes. Peak exercise capacity (Wpeak) at sea-level and normobaric hypoxia (~3900 m) were determined at least 48 hours apart. At rest and during exercise, heart rate, stroke volume, and cardiac output were measured continuously by noninvasive impedance cardiography while arterial oxygen saturation (SaO2) was measured by pulse oximetry.
Heart rate, stroke volume, and cardiac output at rest did not change from sea-level to normobaric hypoxia in males or females and both genders demonstrated similar reductions in arterial oxygen saturation at rest. Peak exercise capacity was significantly reduced from sea-level to normobaric hypoxia in both genders. The relative decrease in peak exercise capacity from sea-level to normobaric hypoxia was significantly greater in males than females. Peak cardiac output was similarly reduced in both genders from sea-level to normobaric hypoxia, while peak stroke volume did not change and peak heart rate was reduced in males more than females. Arterial oxygen saturation at peak was similarly reduced in both genders from sea-level to normobaric hypoxia.
Implication. Endurance trained females appear to be more capable of preserving peak exercise capacity during acute normobaric hypoxia than endurance trained males despite similar decrements in cardiac output and arterial oxygen saturation.
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