Alveolar epithelial integrity in athletes with exercise-induced hypoxemia

Abstract

The effect of incremental exercise to exhaustion on the change in pulmonary clearance rate ( k) of aerosolized99mTc-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA) and the relationship between k and arterial Po 2 (PaO2 ) during heavy work were investigated. Ten male cyclists (age = 25 ± 2 yr, height = 180.9 ± 4.0 cm, mass = 80.1 ± 9.5 kg, maximal O2 uptake = 5.25 ± 0.35 l/min, mean ± SD) completed a pulmonary clearance test shortly (39 ± 8 min) after a maximal O2 uptake test. Resting pulmonary clearance was completed ≥24 h before or after the exercise test. Arterial blood was sampled at rest and at 1-min intervals during exercise. Minimum PaO2 values and maximum alveolar-arterial Po 2 difference ranged from 73 to 92 Torr and from 30 to 55 Torr, respectively. No significant difference between resting k and postexercise kfor the total lung (0.55 ± 0.20 vs. 0.57 ± 0.17 %/min, P > 0.05) was observed. Pearson product-moment correlation indicated no significant linear relationship between change in k for the total lung and minimum PaO2 ( r = −0.26, P > 0.05). These results indicate that, averaged over subjects, pulmonary clearance of99mTc-DTPA after incremental maximal exercise to exhaustion in highly trained male cyclists is unchanged, although the sampling time may have eliminated a transient effect. Lack of a linear relationship between k and minimum PaO2 during exercise suggests that exercise-induced hypoxemia occurs despite maintenance of alveolar epithelial integrity.