Diffusion capacity of the lung in young and old endurance athletes

Lung diffusion capacity (D LCO) declines with age. A significant proportion of older endurance athletes develop exercise-induced hypoxemia (SaO2<95%). We hypothesised that master endurance athletes have a lower D LCO than age-matched non-athletes. We recruited 33 control (16 young; 17 old) and 29 male endurance athletes (13 young; 16 old) during the World Masters Athletics Indoor Championships, 2012 (Jyväskylä, Finland). To measure D LCO the participant exhaled to residual volume and then quickly inhaled to ≥ 90% total lung capacity from a gas source with 0.3% carbon monoxide. The D LCO and transfer coefficient (K CO) were corrected for the actual haemoglobin concentration. Spirometric function was similar in athletes and age-matched controls. D LCO and K CO were 33% and 25% lower in old and young controls, respectively (P<0.001). Although predicted D LCO and K CO were 11%-points higher in athletes than age-matched controls (P<0.001), they were 23% and 16% lower in old athletes than young controls, respectively (P<0.001). D LCO did not correlate with age-graded performance or weekly training hours. The better lung diffusion capacity in male endurance athletes than age-matched controls might be an adaptation to training, self-selection and/or attrition bias. However, the diffusion capacity of the older athlete is lower than that of the young non-athlete.