Prior maximal exercise decreases pulmonary diffusing capacity during subsequent exercise

Area of Science:

• Exercise Physiology
• Pulmonary Function Testing

Background:

• Pulmonary diffusing capacity (DLCO) normally increases with exercise due to enhanced pulmonary capillary volume (Vc) and membrane diffusing capacity (DM).
• A reduction in resting DLCO is observed after strenuous exercise, but its impact on subsequent exercise responses is unclear.

Purpose of the Study:

• To investigate if post-exercise DLCO reduction affects the normal increase in DLCO, Vc, and DM during subsequent exercise.
• To determine if prior exercise impacts SpO2 (pulse oximeter) during subsequent exercise bouts.

Main Methods:

• DLCO, Vc, DM, cardiac output, and SpO2 were measured at rest, moderate (~70% VO2peak), and heavy (~90% VO2peak) exercise.
• Measurements were taken during two exercise sessions separated by approximately 90 minutes in 9 healthy subjects.

Main Results:

• DLCO, Vc, and DM increased significantly during exercise in both sessions.
• DLCO and Vc were lower in the second session compared to the first, with reductions more pronounced at high-intensity exercise.
• SpO2 decreased from rest to high-intensity exercise similarly in both sessions, indicating no significant effect of prior exercise.

Conclusions:

• A bout of high-intensity exercise reduces resting and exercising DLCO and Vc.
• These reductions may be exacerbated during subsequent high-intensity exercise.
• Despite reductions in DLCO and Vc, SpO2 remains unaffected by prior exercise, suggesting preserved oxygen saturation during repeated exercise bouts.