AUTHOR=Osmani Florent , Lago-Fuentes Carlos , Alemany-Iturriaga Josep , Barcala-Furelos Martín 

TITLE=The relationship of muscle oxygen saturation analyzer with other monitoring and quantification tools in a maximal incremental treadmill test

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1155037

DOI=10.3389/fphys.2023.1155037

ISSN=1664-042X

ABSTRACT=<p><bold>Introduction:</bold> The study aims to explore whether NIRS derived data can be used to identify the second ventilatory threshold (VT2) during a maximal incremental treadmill test in non-professional runners and to determine if there is a correlation between SmO<sub>2</sub> and other valid and reliable exercise performance assessment measures or parameters for maximal incremental test, such as lactate concentration (LT), RPE, HR, and running power (W).</p><p><bold>Methods:</bold> 24 participants were recruited for the study (5 women and 19 men). The devices used consisted of the following: i) a muscle oxygen saturation analyzer placed on the vastus lateralis of the right leg, ii) the Stryd power meter for running, iii) the Polar H7 heart rate band; and iv) the lactate analyzer. In addition, a subjective perceived exertion scale (RPE 1-10) was used. All of the previously mentioned devices were used in a maximal incremental treadmill test, which began at a speed of 8 km/h with a 1% slope and a speed increase of 1.2 km/h every 3 min. This was followed by a 30-s break to collect the lactate data between each 3-min stage. Spearman correlation was carried out and the level of significance was set at <italic>p</italic> &lt; 0.05.</p><p><bold>Results:</bold> The VT2 was observed at 87,41 ± 6,47% of the maximal aerobic speed (MAS) of each participant. No relationship between lactate data and SmO<sub>2</sub> values (<italic>p</italic> = 0.076; <italic>r</italic> = −0.156) at the VT2 were found. No significant correlations were found between the SmO<sub>2</sub> variables and the other variables (<italic>p</italic> &gt; 0.05), but a high level of significance and strong correlations were found between all the following variables: power data (W), heart rate (HR), lactate concentration (LT) and RPE (<italic>p</italic> &lt; 0.05; <italic>r</italic> &gt; 0.5).</p><p><bold>Discussion:</bold> SmO<sub>2</sub> data alone were not enough to determine the VT2, and there were no significant correlations between SmO<sub>2</sub> and the other studied variables during the maximal incremental treadmill test. Only 8 subjects had a breakpoint at the VT2 determined by lactate data.</p><p><bold>Conclusion:</bold> The NIRS tool, Humon Hex, does not seem to be useful in determining VT2 and it does not correlate with the other variables in a maximal incremental treadmill test.</p>