The role of airflow limitation in exercise-induced arterial hypoxemia

The role of airflow limitation (AFL) in exercise-induced arterial hypoxemia (ElAH) was examined in six well-trained competitive cyclists. Two maximal cycle ergometer tests were performed, one while breathing room air (RA; 79% N2, 21% O2) and another breathing a mixture of heliox (He; 79% He, 21% O2) in random order. EIAH was estimated via pulse oximetry of HbSaO2. The results revealed no subject experienced AFL breathing RA or He. Despite a significant increase in V&dot;Emax (RA = 114.3 +/- 27.6 l/min; He = 129.2 +/- 25.5 l/min; p < 0.05) during He condition there was no difference in HbSaO2 during maximal exercise (RA = 95.3 +/- 1%; He = 96.7 +/- 1.5%; p > 0.05). In conclusion, our subject population failed to show any significant decrease in HbSaO2 breathing RA, which makes it difficult to determine if AFL plays a role in EIAH.