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Updated: Sep 9, 2025
Supramaximal Intensity Hypoxic Exercise and Vascular Function Assessment in Mice
Published on: March 15, 2019
Cardiorespiratory and oxygenation responses in iron-deficient anemic women during whole-body exercise under moderate
Panagiotis G Miliotis1, Spyridoula D Ntalapera2, Panagiotis Lakeas2,3
1Division of Sport Medicine and Biology of Exercise, School of Physical Education and Sport Science, National and Kapodistrian University of Athens, Athens, Greece. pmiliotis@phed.uoa.gr.
Purpose:
Integrated physiological responses during maximal whole-body exercise, such as cycling, under additive hypoxemia (anemia + hypoxia) are not adequately studied. Therefore, we investigated cardiovascular, muscular and cerebral oxygenation responses in chronic mildly iron-deficient and control women under normoxic and moderate hypoxic conditions during maximal whole-body exercise.
Methods:
In a randomized and counterbalanced order, 16 females performed incremental exercise to exhaustion under normoxia (N; FIO2:20.94%) and hypoxia (H; FIO2:13.6%). The participants were divided into two groups matched for age and anthropometric characteristics, but intentionally varying in [Hb] (p < 0.001) and V̇O2max (p < 0.01); iron-deficient (A; n = 8; [Hb]:11.3 ± 0.4 g/dl; V̇O2max:37.3 ± 2.8 ml/kg/min) and healthy controls (C; n = 8; [Hb]:13.3 ± 0.4 g/dl; V̇O2max:40.8 ± 1.9 ml/kg/min).
Results:
During exercise in hypoxia compared to normoxia, the A exhibited greater decrement in V̇O2max (5.0%; p = 0.02) and peak power output (5.4%; p = 0.004) than C. Maximal mean arterial pressure was reduced (p < 0.05) due to lower total peripheral resistance (p < 0.05) and unchanged maximal cardiac output (p > 0.05). Enhanced O2 utilization under H was observed only in C, based on ΔHHb (p < 0.05). Cerebral oxygenation was reduced linearly with CaO2 (r = 0.95, p < 0.001).
Conclusion:
Collectively, moderate hypoxia induced greater reduction of V̇O2max, peak power output and cerebral oxygenation leading to exercise intolerance in A compared to C. These responses were accompanied by an inability of skeletal muscle to increase O2 utilization at maximal effort in H and by a failure of the cardiovascular system to compensate and counteract convective and diffusion limitations during maximal whole-body exercise in anemic women.
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