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: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-04-01
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| Series: | Journal of Functional Morphology and Kinesiology |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2411-5142/10/2/136 |
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| Summary: | <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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| ISSN: | 2411-5142 |