Abstract
Pulmonary diffusion (D-LCO) increases during exercise due to greater pulmonary capillary volume (Vc) and membrane diffusing capacity (D-M). However, after heavy exercise there is a reduction in resting D-LCO. It is unclear whether this post-exercise effect will attenuate the normal increase in D-LCO, V-c and D-M during subsequent exercise and whether this affects SpO(2) (pulse oximeter). D-LCO, V-c, D-M, cardiac output and SpO(2) were measured at rest, moderate (similar to 70 % VO2peak) and heavy (similar to 90 VO2peak) exercise in 9 subjects during 2 sessions separated by similar to 90 min. D-LCO, V-c and D-M increased during exercise (P < 0.05). D-LCO (P < 0.05) and V-c (P < 0.10), but not D-M or SpO(2) were lower in session 2 compared to the first. Reductions in D-LCO and Vc appeared to be smallest during rest (1-4 %) and greatest at high-intensity exercise (8-20 %), but the interaction was not significant. SpO(2) decreased by 4.9 % and 5.1 % from rest to high-intensity exercise during the first and second exercise bout, but these changes were not different. These data confirm that a bout of high-intensity exercise reduces D-LCO and V-c, and may indicate that these changes are exacerbated during subsequent high-intensity exercise. Despite these changes, SpO(2) was not affected by previous exercise.