Cardiac output with modified cardio-impedance against inert gas rebreathing during sub-maximal and maximal cycling exercise in healthy and fit subjects

Purpose We measured cardiac output (\(\dot {Q}\)) during sub-maximal and supra-maximal exercise with inert gas rebreathing (\({\dot {Q}_{{\text{IN}}}}\)) and modified cardio-impedance (\({\dot {Q}_{{\text{PF}}}}\)) and we evaluated the repeatability of the two methods.