Model analysis on alveolar-capillary O2 equilibration during exercise

The present article was aimed at determining the alveolar-capillary PO2 difference (ΔPAc¯O2) during exercise. The working hypothesis was that values of the pulmonary NO diffusing capacity can be used to calculate ΔPAc¯O2 data on the basis of well-known laws of pulmonary gas exchange. For this purpose, we analysed the pertinent data of three studies performed on 35 healthy, non-athletic non-smokers of similar age at seven different exercise intensities. Calculated mean values of alveolar-capillary PO2 difference aggravated from ΔPAc¯O2=2mmHg at rest to ΔPAc¯O2=18mmHg at a performance capacity amounting to 90% of the maximum level. Regression analysis revealed ΔPAc¯O2=0.31·(V˙O2/V˙O2max)-0.0012·(V˙O2/V˙O2max)2 at a very high significance level (n = 7, r = 0.999, P < 0.0000082). Due to the non-linear increase of ΔPAc¯O2 with inclining O2 consumption, our model analysis confirms the opinion that pulmonary diffusion decreasingly determines maximal aerobic power.