AUTHOR=Kasiak Przemysław , Kowalski Tomasz , Rębiś Kinga , Klusiewicz Andrzej , Starczewski Michał , Ładyga Maria , Wiecha Szczepan , Barylski Marcin , Poliwczak Adam Rafał , Wierzbiński Piotr , Mamcarz Artur , Śliż Daniel 

TITLE=Below or all the way to the peak? Oxygen uptake efficiency slope as the index of cardiorespiratory response to exercise—the NOODLE study

JOURNAL=Frontiers in Physiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2024.1348307

DOI=10.3389/fphys.2024.1348307

ISSN=1664-042X

ABSTRACT=<p><bold>Background:</bold> The ratio of oxygen uptake (VO<sub>2</sub>) to minute ventilation (VE) is described as the oxygen uptake efficiency slope (OUES). OUES has been suggested as a valuable submaximal cardiorespiratory index; however, its characteristics in endurance athletes remain unknown. In this study, we a) investigated OUES between different time intervals, b) assessed their prediction power for VO<sub>2</sub>peak, and c) derived new prediction equations for OUES tailored for well-trained individuals.</p><p><bold>Materials and Methods:</bold> A total of 77 male (age = 21.4 ± 4.8 yrs; BMI = 22.1 ± 1.6 kg·m<sup>−2</sup>; peak oxygen uptake = 4.40 ± 0.64 L·min<sup>−1</sup>) and 63 female individuals (age = 23.4 ± 4.3 yrs; BMI = 23.1 ± 1.6 kg·m<sup>−2</sup>; peak oxygen uptake = 3.21 ± 0.48 L·min<sup>−1</sup>) underwent the cycling cardiopulmonary exercise test. OUES was measured at 75%, 90%, and 100% of exercise duration. Prediction power and new models were derived with the multiple linear regression method.</p><p><bold>Results:</bold> In male subjects, OUES [mL·min<sup>−1</sup>/L·min<sup>−1</sup>] from 75% = 4.53 ± 0.90, from 90% = 4.52 ± 0.91, and from 100% = 4.41 ± 0.87. In female subjects, OUES [mL·min<sup>−1</sup>/L·min<sup>−1</sup>] from 75% = 3.50 ± 0.65, from 90% = 3.49 ± 0.62, and from 100% = 3.41 ± 0.58. OUES did not differ between time intervals in male (<italic>p</italic> = 0.65) and female individuals (<italic>p</italic> = 0.69). OUES strongly predicts peak VO<sub>2</sub> independently from the measuring interval (<italic>β</italic> = 0.71–0.80; <italic>R</italic><sup>2</sup> = 0.50–0.63). The prediction model designed for elite athletes was OUES [mL·min<sup>−1</sup>/L·min<sup>−1</sup>] = −1.54 + 2.99; BSA [m<sup>2</sup>]—0.0014; (age [in years]; sex [1 = male, 2 = female]) (<italic>R</italic><sup>2</sup> = 0.36).</p><p><bold>Conclusion:</bold> OUES enables an accurate prediction of peak cardiorespiratory fitness in elite endurance athletes. OUES is a feasible alternative to maximal exercise testing. A new prediction equation should be used for highly trained individuals. Physicians should understand OUES physiology to properly assess the cardiorespiratory response to exercise in athletic cohorts.</p>