Temporal dissociation between muscle and pulmonary oxygen uptake kinetics: influences of perfusion dynamics and arteriovenous oxygen concentration differences in muscles and lungs

Abstract

Purpose: The aim of the study was to test whether or not the arteriovenous oxygen concentration difference (avDO2) kinetics at the pulmonary (avDO2pulm) and muscle (avDO2musc) levels is significantly different during dynamic exercise. Methods: A re-analysis involving six publications dealing with kinetic analysis was utilized with an overall sample size of 69 participants. All studies comprised an identical pseudorandom binary sequence work rate (WR) protocol—WR changes between 30 and 80 W—to analyze the kinetic responses of pulmonary (V˙ O 2pulm) and muscle (V˙ O 2musc) oxygen uptake kinetics as well as those of avDO2pulm and avDO2musc. Results: A significant difference between V˙ O 2musc (0.395 ± 0.079) and V˙ O 2pulm kinetics (0.330 ± 0.078) was observed (p < 0.001), where the variables showed a significant relationship (rSP = 0.744, p < 0.001). There were no significant differences between avDO2musc (0.446 ± 0.077) and avDO2pulm kinetics (0.451 ± 0.075), which are highly correlated (r = 0.929, p < 0.001). Conclusion: It is suggested that neither avDO2pulm nor avDO2musc kinetic responses seem to be responsible for the differences between estimated V˙ O 2musc and measured V˙ O 2pulm kinetics. Obviously, the conflation of avDO2 and perfusion (Q˙) at different points in time and at different physiological levels drive potential differences in V˙ O 2pulm and V˙ O 2musc kinetics. Therefore, Q˙ should, in general, be considered whenever oxygen uptake kinetics are analyzed or discussed.