Determination of the Respiratory Compensation Point by Detecting Changes in Intercostal Muscles Oxygenation by Using Near-Infrared Spectroscopy
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Date
2022
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Abstract
This study aimed to evaluate if the changes in oxygen saturation levels at intercostal muscles (SmO2 m.intercostales) assessed by near-infrared spectroscopy (NIRS) using a wearable device could determine the respiratory compensation point (RCP) during exercise. Fifteen healthy competitive triathletes (eight males; 29 +/- 6 years; height 167.6 +/- 25.6 cm; weight 69.2 +/- 9.4 kg; (V) over dotO(2)-max 58.4 +/- 8.1 mL.kg(-1).min(-1)) were evaluated in a cycle ergometer during the maximal oxygen-uptake test ((V) over dotO(2)-max), while lung ventilation ((V) over dotE), power output (watts, W) and SmO2 mantercostales were measured. RCP was determined by visual method (RCPvisual : changes at ventilatory equivalents ((V) over dotE.CO2-1, (V) over dotE.(V) over dotO(2)(-1)) and end-tidal respiratory pressure (PetO(2), PetCO(2)) and NIRS method (RCP NIRS : breakpoint of fall in SmO2 m.intercostales). During exercise, SmO2 m.intercostales decreased continuously showing a higher decrease when (V) over dotE increased abruptly. A good agreement between methods used to determine RCP was found (visual vs NIRS) at %(V) over dotO(2)-max, (V) over dotO(2), (V) over dotE, and W (Bland-Altman test). Correlations were found to each parameters analyzed (r = 0.854; r = 0.865; r = 0.981; and r = 0,968; respectively. p < 0.001 in all variables, Pearson test), with no differences (p < 0.001 in all variables, Student's t-test) between methods used (RCPvisual and RCPNIRS). We concluded that changes at SmO2 m.intercostales measured by NIRS could adequately determine RCP in triathletes.
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Keywords
Exercise, Near-infrared spectroscopy, Respiratory muscles, Oxygen uptake, Respiratory compensation point