Exercise-induced hypoxemia in older athletes.

To determine whether exercise induces hypoxemia in highly trained older "master" athletes (MA), as it does in certain elite endurance-trained young athletes (YA), 10 MA (65.3 +/- 2.6 yr), 10 control subjects (CS; 68.3 +/- 2.2 yr), and 10 endurance-trained YA (23.3 +/- 1.1 yr) performed an incremental exercise test. During testing, blood samples for arterial blood gas analysis were drawn during the last 20 s of each load. Lung exchanges were measured using a breath-by-breath automated exercise device. Exercise-induced hypoxemia (EIH) appeared in all MA and 8 of 10 YA, whereas there were no changes in the blood gases of CS. In MA, arterial PO2 decreased significantly from 40% of maximal O2 uptake onward and was associated with a significant increase in the ideal alveolar-arterial O2 difference from 60% onward. The MA also showed a lower ventilation for a given absolute load compared with CS. In all subjects arterial PCO2 rose slightly but significantly during the work, but this increase was most marked in MA. The EIH differed between MA and YA in the following ways: 1) all MA showed a drop in arterial PO2 during exercise, 2) this drop appeared earlier and was significantly greater for a given load in MA, and 3) EIH appeared at a lower level of training regimen in MA. This hypoxemia was at first isolated, probably at least partially due to relative hypoventilation, and then was associated with a widened ideal alveolar-arterial O2 difference, which may have been due to an increase in extravascular lung water.(ABSTRACT TRUNCATED AT 250 WORDS)