Reliability of Muscle Oxygen Saturation for Evaluating Exercise Intensity and Knee Joint Load Indicators

<b>Objectives:</b> This study aimed to evaluate the reliability of muscle oxygen saturation (SmO<sub>2</sub>) and its correlation with variables from an inertial measurement unit (IMU) sensor placed on the knee at different exercise intensities. <b>Methods:</b> Fo...

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Main Authors: Aldo A. Vasquez-Bonilla, Rodrigo Yáñez-Sepúlveda, Matías Monsalves-Álvarez, Marcelo Tuesta, Daniel Duclos-Bastías, Guillermo Cortés-Roco, Jorge Olivares-Arancibia, Eduardo Guzmán-Muñoz, José Francisco López-Gil
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Journal of Functional Morphology and Kinesiology
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Online Access:https://www.mdpi.com/2411-5142/10/2/136
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author Aldo A. Vasquez-Bonilla
Rodrigo Yáñez-Sepúlveda
Matías Monsalves-Álvarez
Marcelo Tuesta
Daniel Duclos-Bastías
Guillermo Cortés-Roco
Jorge Olivares-Arancibia
Eduardo Guzmán-Muñoz
José Francisco López-Gil
author_facet Aldo A. Vasquez-Bonilla
Rodrigo Yáñez-Sepúlveda
Matías Monsalves-Álvarez
Marcelo Tuesta
Daniel Duclos-Bastías
Guillermo Cortés-Roco
Jorge Olivares-Arancibia
Eduardo Guzmán-Muñoz
José Francisco López-Gil
author_sort Aldo A. Vasquez-Bonilla
collection DOAJ
description <b>Objectives:</b> This study aimed to evaluate the reliability of muscle oxygen saturation (SmO<sub>2</sub>) and its correlation with variables from an inertial measurement unit (IMU) sensor placed on the knee at different exercise intensities. <b>Methods:</b> Fourteen university athletes participated in the study. Incremental ergospirometry was performed to exhaustion to calculate V’O<sub>2</sub>max, determine training zones, heart rate, and workload using the IMU, and analyze muscle metabolism by SmO<sub>2</sub>. <b>Results:</b> The analysis revealed significant differences between moderate-to-high-intensity zones (80–89% vs. 50–69%, Δ = 27% of SmO<sub>2</sub>; <i>p</i> < 0.001) and high-intensity zones (90–100% vs. 50–79%, Δ = 35% of SmO<sub>2</sub>; <i>p</i> < 0.001). SmO<sub>2</sub> values showed moderate reliability at moderate exercise intensities (e.g., ICC 0.744 at 50%) and high variability at higher intensities, with ICC values around 0.577–0.594, and CV% increasing up to 77.7% at 100% intensity, indicating decreasing consistency as exercise intensity increases. SmO<sub>2</sub> significantly decreases with increasing angular velocity (β = −13.9, <i>p</i> < 0.001), while knee joint load only shows significant correlations with SmO<sub>2</sub> in the moderate-to-high-intensity zones (r = 0.569, <i>p</i> = 0.004) and high-intensity zones (r = 0.455, <i>p</i> = 0.012). <b>Conclusions:</b> SmO<sub>2</sub> is a key predictor of performance during maximal incremental exercise, particularly in high-intensity zones. Moreover, SmO<sub>2</sub> has the potential to serve as a physiological marker of the internal load on the muscles surrounding the knee during exercise. The SmO<sub>2</sub> decrease could depend on the angular velocity and impact of the exposed knee during running.
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spelling doaj-art-1272550bb38847fcba6ca8f62cb2b4982025-08-20T02:21:07ZengMDPI AGJournal of Functional Morphology and Kinesiology2411-51422025-04-0110213610.3390/jfmk10020136Reliability of Muscle Oxygen Saturation for Evaluating Exercise Intensity and Knee Joint Load IndicatorsAldo A. Vasquez-Bonilla0Rodrigo Yáñez-Sepúlveda1Matías Monsalves-Álvarez2Marcelo Tuesta3Daniel Duclos-Bastías4Guillermo Cortés-Roco5Jorge Olivares-Arancibia6Eduardo Guzmán-Muñoz7José Francisco López-Gil8Faculty of Sport Sciences, University of Extremadura, 10001 Caceres, SpainFaculty Education and Social Sciences, Universidad Andres Bello, Viña del Mar 2520000, ChileExercise and Rehabilitation Sciences Institute, Faculty of Rehabilitation Sciences, Universidad Andres Bello, Santiago 7550000, ChileExercise and Rehabilitation Sciences Institute, Faculty of Rehabilitation Sciences, Universidad Andres Bello, Santiago 7550000, ChileiGEO Group, School of Physical Education, Pontificia Universidad Católica de Valparaíso, Valparaíso 2340000, ChileFaculty of Life Sciences, Universidad Viña del Mar, Viña del Mar 2520000, ChileGrupo AFySE, Investigación en Actividad Física y Salud Escolar, Escuela de Pedagogía en Educación Física, Facultad de Educación, Universidad de las Américas, Santiago 8320000, ChileEscuela de Kinesiología, Facultad de Salud, Universidad Santo Tomás, Talca 3460000, ChileOne Health Research Group, Universidad de Las Américas, Quito 170124, Ecuador<b>Objectives:</b> This study aimed to evaluate the reliability of muscle oxygen saturation (SmO<sub>2</sub>) and its correlation with variables from an inertial measurement unit (IMU) sensor placed on the knee at different exercise intensities. <b>Methods:</b> Fourteen university athletes participated in the study. Incremental ergospirometry was performed to exhaustion to calculate V’O<sub>2</sub>max, determine training zones, heart rate, and workload using the IMU, and analyze muscle metabolism by SmO<sub>2</sub>. <b>Results:</b> The analysis revealed significant differences between moderate-to-high-intensity zones (80–89% vs. 50–69%, Δ = 27% of SmO<sub>2</sub>; <i>p</i> < 0.001) and high-intensity zones (90–100% vs. 50–79%, Δ = 35% of SmO<sub>2</sub>; <i>p</i> < 0.001). SmO<sub>2</sub> values showed moderate reliability at moderate exercise intensities (e.g., ICC 0.744 at 50%) and high variability at higher intensities, with ICC values around 0.577–0.594, and CV% increasing up to 77.7% at 100% intensity, indicating decreasing consistency as exercise intensity increases. SmO<sub>2</sub> significantly decreases with increasing angular velocity (β = −13.9, <i>p</i> < 0.001), while knee joint load only shows significant correlations with SmO<sub>2</sub> in the moderate-to-high-intensity zones (r = 0.569, <i>p</i> = 0.004) and high-intensity zones (r = 0.455, <i>p</i> = 0.012). <b>Conclusions:</b> SmO<sub>2</sub> is a key predictor of performance during maximal incremental exercise, particularly in high-intensity zones. Moreover, SmO<sub>2</sub> has the potential to serve as a physiological marker of the internal load on the muscles surrounding the knee during exercise. The SmO<sub>2</sub> decrease could depend on the angular velocity and impact of the exposed knee during running.https://www.mdpi.com/2411-5142/10/2/136skeletal musclekneeexerciseoxygen uptakeangular velocity
spellingShingle Aldo A. Vasquez-Bonilla
Rodrigo Yáñez-Sepúlveda
Matías Monsalves-Álvarez
Marcelo Tuesta
Daniel Duclos-Bastías
Guillermo Cortés-Roco
Jorge Olivares-Arancibia
Eduardo Guzmán-Muñoz
José Francisco López-Gil
Reliability of Muscle Oxygen Saturation for Evaluating Exercise Intensity and Knee Joint Load Indicators
Journal of Functional Morphology and Kinesiology
skeletal muscle
knee
exercise
oxygen uptake
angular velocity
title Reliability of Muscle Oxygen Saturation for Evaluating Exercise Intensity and Knee Joint Load Indicators
title_full Reliability of Muscle Oxygen Saturation for Evaluating Exercise Intensity and Knee Joint Load Indicators
title_fullStr Reliability of Muscle Oxygen Saturation for Evaluating Exercise Intensity and Knee Joint Load Indicators
title_full_unstemmed Reliability of Muscle Oxygen Saturation for Evaluating Exercise Intensity and Knee Joint Load Indicators
title_short Reliability of Muscle Oxygen Saturation for Evaluating Exercise Intensity and Knee Joint Load Indicators
title_sort reliability of muscle oxygen saturation for evaluating exercise intensity and knee joint load indicators
topic skeletal muscle
knee
exercise
oxygen uptake
angular velocity
url https://www.mdpi.com/2411-5142/10/2/136
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