Validity and Practical Application of Muscle Oxygenation Monitoring for Identifying Maximal Fat Oxidation in Cyclists

Area of Science:

• Exercise Physiology
• Sports Science
• Biomedical Engineering

Background:

• Accurate identification of physiological milestones like maximal fat oxidation (MFO) is crucial for optimizing cycling performance and training.
• Traditional methods for determining MFO can be complex and costly, necessitating simpler, noninvasive alternatives.
• Near-infrared spectroscopy (NIRS) offers a noninvasive approach to measure physiological variables, showing potential for practical application in sports science.

Purpose of the Study:

• To evaluate the validity of a muscular oxygen saturation visualization methodology using NIRS for identifying the precise MFO point in trained cyclists.
• To compare NIRS-derived MFO detection with traditional gas analysis methods in a controlled laboratory setting.

Main Methods:

• Twenty-two recreational endurance-trained cyclists underwent submaximal and maximal exercise tests on a single day.
• Muscular oxygen saturation was monitored using NIRS technology.
• Data from the NIRS visualization methodology were compared against a criterion gas analyzer to assess validity for MFO detection.

Main Results:

• The NIRS visualization methodology did not accurately identify the precise point of maximal fat oxidation (MFO) (bias = 90 ± 218 s, LOA = 429 s).
• However, the technique showed potential for identifying the MFO zone, with acceptable biases for heart rate (4.7 ± 11.9 bpm) but less so for oxygen uptake (1.49 ± 5.7 mL/kg/min) and power output (19.5 ± 31.2 W).
• Concordance coefficients indicated limited agreement for oxygen uptake (0.243) and power output (0.170), suggesting NIRS is not suitable for precise MFO detection but may indicate a broader zone.

Conclusions:

• The NIRS device and visualization methodology employed in this study are not sufficiently accurate for detecting the precise point of maximal fat oxidation (MFO) in trained cyclists.
• Despite limitations in pinpointing MFO, the NIRS technique may serve as a valid tool for identifying the general MFO zone during exercise.
• Further research is warranted to refine NIRS methodologies for more accurate assessment of metabolic parameters like MFO in athletic populations.