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

## TL;DR

This study evaluates whether muscle oxygenation monitoring using NIRS can help identify the maximal fat oxidation point in cyclists, finding it useful for estimating a general zone but not the exact point.

## Contribution

The study introduces a practical, noninvasive method using NIRS for approximating the MFO zone in cyclists.

## Key findings

- NIRS does not accurately pinpoint the exact MFO point but can identify a general zone.
- The technique is practical for coaches who need a simpler alternative to complex methods.
- Biases in heart rate, VO2, and power were moderate, with high concordance for heart rate.

## Abstract

The accurate detection of several physiological milestones, such as maximal fat oxidation (MFO), is an important factor for cycling performance and for programming effective and individualised training. However, the procedure to identify the MFO is often too complex and expensive. Near‐infrared spectroscopy (NIRS) technology provides a noninvasive measurement that can be used to detect different physiological variables. The aim of this study was to assess the validity of utilising the muscular oxygen saturation visualisation methodology for the identification of the MFO point in trained cyclists. Twenty‐two recreational endurance‐trained cyclists (19 men and 3 women; age: 27.9 ± 5.4 years; body mass: 69.7 ± 7.1 kg and VO2max: 60.3 ± 7.0 mL/kg/min) performed a submaximal and maximal exhaustion test. All the data were collected on a single day. The validity of the visualisation methodology for the maximal fat oxidation point was analysed against a gas analyser. The detection of maximal fat oxidation (MFO) using the methodology and device employed does not appear to accurately specify the precise point at which MFO occurs (bias = 90 ± 218 s and LOA = 429 s). However, our results indicate that it may be a valid technique for identifying the MFO zone; biases were HR = 4.7 ± 11.9 bpm, VO2 = 1.49 ± 5.7 mL/kg/min and power = 19.5 ± 31.2 W, whereas the concordance coefficients were 0.783, 0.243 and 0.170, respectively. It is not possible to detect MFO using NIRS device. However, it is possible to detect a general zone in which MFO occurs.

The detection of the maximal fat oxidation point using muscle oxygen saturation plotted as a function of time does not appear to accurately specify the precise point at which maximal fat oxidation occurs.It is possible to detect a general zone in which the maximal fat oxidation occurs.Near‐infrared spectroscopy technology is useful for coaches without time to do complicated analyses.

The detection of the maximal fat oxidation point using muscle oxygen saturation plotted as a function of time does not appear to accurately specify the precise point at which maximal fat oxidation occurs.

It is possible to detect a general zone in which the maximal fat oxidation occurs.

Near‐infrared spectroscopy technology is useful for coaches without time to do complicated analyses.