Physiological Responses of Anemic Women to Exercise under Hypoxic Conditions

Abstract

When combining two conditions of reduced oxygen availability, anemia and hypoxia, human physiological responses are highly challenged to maintain arterial oxygen delivery, especially during whole-body exercise. The aim of this study was to compare the cardiorespiratory responses of mildly anemic women with those of healthy controls, while cycling in normobaric hypoxia. Two groups of young females were matched for age, weight, height, and involvement in physical activity, one with normal hemoglobin, hematocrit, and ferritin levels and another suffering from mild iron deficiency anemia (10 < (Hb) < 12 g/dL, 34 < Hct < 37%, ferritin < 15 μg/L). They cycled to exhaustion under normoxia and hypoxia (FIO2 0.21 and 0.14), and their physiological responses were compared at 40, 80, and 100% VO2max of the specific condition. The two groups differed (p < 0.05) mainly at the higher exercise intensities; the anemic participants exhibited similar heart rate but lower oxygen pulse than their control counterparts, as well as a larger drop in maximal oxygen uptake. However, they sustained maximal effort by employing the anaerobic metabolism to a larger extent, which stimulated a greater ventilatory response. It appears that iron deficiency anemia of mild severity, which is commonly observed in young athletic females, impacts physiological responses during whole-body exercise in the presence of moderate hypoxia.