Exercise-induced hypoxemia in athletes: Role of inadequate hyperventilation |
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Authors: | Scott K Powers Daniel Martin Michael Cicale Nancy Collop David Huang David Criswell |
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Institution: | (1) Center for Exercise Science, Departments of Exercise and Sport Sciences, Physical Therapy, Medicine, and Physiology, University of Florida, 32611 Gainesville, FL, USA |
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Abstract: | Summary These experiments examined the exercise-induced changes in pulmonary gas exchange in elite endurance athletes and tested the hypothesis that an inadequate hyperventilatory response might explain the large intersubject variability in arterial partial pressure of oxygen (P
a02) during heavy exercise in this population. Twelve highly trained endurance cyclists maximum oxygen consumption (VO2max) range = 65-77 ml·kg–1·min–1] performed a normoxic graded exercise test on a cycle ergometer toVO2max at sea level. During incremental exercise atVO2max 5 of the 12 subjects had ideal alveolar to arterial P02 gradients (P
A-aO2) of above 5 kPa (range 5-5.7) and a decline from restingP
aO2 ( P
aO2) 2.4 kPa or above (range 2.4-2.7). In contrast, 4 subjects had a maximal exercise (P
A-aO2) of 4.0-4.3 kPa with P
aO2 of 0.4-1.3 kPa while the remaining 3 subjects hadP
A-aO2 of 4.3-5 kPa with P
aO2 between 1.7 and 2.0 kPa. The correlation between PAO2 andP
aO2 atVO2max was 0.17. Further, the correlation between the ratio of ventilation to oxygen consumption VSP
aO2 and arterial partial pressure of carbon dioxide VSP
aO2 atVO2max was 0.17 and 0.34, respectively. These experiments demonstrate that heavy exercise results in significantly compromised pulmonary gas exchange in approximately 40% of the elite endurance athletes studied. These data do not support the hypothesis that the principal mechanism to explain this gas exchange failure is an inadequate hyperventilatory response. |
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Keywords: | Alveolar-arterialPO2 difference Pulmonary gas exchange VO2max Hypoxia Hyperoxia |
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