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 ( \(\dot {V}_2}{\text{pulm}}\) ) and muscle ( \(\dot {V}_2}{\text{musc}}\) ) oxygen uptake kinetics as well as those of avDO₂pulm and avDO₂musc.

Results

A significant difference between \(\dot {V}_2}{\text{musc}}\) (0.395 ± 0.079) and \(\dot {V}_2}{\text{pulm}}\) kinetics (0.330 ± 0.078) was observed (p < 0.001), where the variables showed a significant relationship (r_SP = 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 \(\dot {V}_2}{\text{musc}}\) and measured \(\dot {V}_2}{\text{pulm}}\) kinetics. Obviously, the conflation of avDO₂ and perfusion ( \({\dot {Q}}\) ) at different points in time and at different physiological levels drive potential differences in \(\dot {V}_2}{\text{pulm}}\) and \(\dot {V}_2}{\text{musc}}\) kinetics. Therefore, \({\dot {Q}}\) should, in general, be considered whenever oxygen uptake kinetics are analyzed or discussed.

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