When it comes to optimizing endurance training, physiological accuracy matters. physiological accuracy matters. Many athletes and coaches use NIRS (near infrared spectroscopy) devices, such as the Moxy Monitor to measure muscle oxygenation during exercise. But here comes the inconvenient fact: not all NIRS devices measure the same thing or in the same way..

Muscle Oxygenation vs. Tissue Oxygenation - The Key Is in What You Actually Measure

The critical difference is which fabric you are reading:

• SmO₂Oxygen saturation in active skeletal muscle. It's the signal you want if you're serious about training.
• StO₂ o TSI: mixture of skin, fat and muscle. Much more contaminated and non-specific.

Moxy is specifically designed to isolate the muscle signal, filtering out "noise" from skin and fat.by filtering out the "noise" of skin and fat.

Now you realize why the data from other devices doesn't add up, or changes too fast... or too slow. It's not your body, it's the sensor.

Moxy: The Only One with Published Scientific Validation

And here is the key point:
Moxy is the only portable NIRS with clinical, sports and comparative studies published in peer-reviewed scientific journals.
In fact, it is the one used as a reference to validate other devices and training protocols.

You can see for yourself at PubMed - more than 60 publications.

Full Physiological Range: 0-100 %.

SmO₂ in muscle works on a real, physiological scale of. 0 % (completely desaturated) a 100 % (fully saturated).
With validated protocols, such as an arterial occlusion, Moxy can record real SmO₂ drops to 5-10 % and rises to 90 % during hyperemia. That is the physiological reality.

In contrast, many NIRS devices show minimums of 40-50 %, even in maximum stress tests. This it is not a calibration failure, it is that they are measuring a mixed signal.. And that makes your data of little use in making real decisions.

*READ THE FOLLOWING STUDY: Muscle oxygen saturation derived from near-infrared spectroscopy on a 0% to 100% scale: reliability and validity of the Moxy Monitor.

Why Should You Measure SmO₂ and Not StO₂/TSI?

Because the difference is not only technical, it is functional and practical..
If you measure SmO₂ realyou can:

• Establish precise physiological thresholds (not just sensations).
• Compare training with consistent data.
• Detect muscle limitations real (if the SmO₂ never goes below 60%, maybe the muscle isn't being demanded... or maybe your device can't measure lower).
• Adapt your decisions to muscle response and not to skin variations.
• Monitor muscle recovery without interference from other tissues.

If you are using a device that measures StO₂ or TSI, beware of comparing absolute valuesespecially in different environments (heat, cold, sweat, skin vasodilation).

Y never compare data between different brandsThey do not speak the same physiological language.

How To Know If Your Sensor Is Measuring Real SmO₂?

Take this test simple:

1. Arterial occlusion test:
   Inflate a cuff above systolic pressure (280 mmHg) for 3-5 minutes.
   → If your device drops to 5-15 %, congratulations! You are measuring SmO₂.
   → If it stays stuck at 45 %, you are seeing StO₂ mixed.
2. Maximum exercise:
   In trained athletes, Moxy can record SmO₂ values below 10 %.
   → If yours never goes below 40 %, you are probably not reading pure muscle.
3. Change of thermal environment:
   If going from cold to hot without changing the exercise the values change a lot, you are probably looking at variations in skin flow, not muscle.

In Summary, Why Moxy Makes the Difference?

Isolated muscle signal
Many NIRS measure skin + muscle and are mistaken for temperature or skin flow.
Moxy filters the dermal pulse and focuses on the working muscle.

2. Actual SmO₂ scale (0-100 %).
Others say "%SmO₂", but do not use an actual physiological scale.
Moxy yes: uses 4 wavelengths and precise tissue modeling.

3. Total hemoglobin (tHb)
Not all devices report it.
Moxy yes, allowing to know oxygen delivery, not just saturation.

4. Subcutaneous fat correction
Grease distorts the readings.
Moxy corrects it automatically according to the thickness of the fabric.

5. Muscular versatility
Some sensors only work on the quadriceps.
Moxy can be applied on quadriceps, soleus, calf, hamstring, deltoid...

6. Thermal stability
Heat affects the light of LEDs.
Moxy compensates in real time.

7. Reliability in the face of tattoos or hair
The basic sensors are affected by these elements.
Moxy minimizes such interference and maintains accuracy.

Conclusion

Moxy is not just another wearable.
It is a professional tool with scientific validity, technical accuracy and real utility for:

• Physiotherapy and muscle rehabilitation
• Threshold training
• Fatigue control
• Recovery optimization
• Clinical and sports research

It is applied science, not posturing.
It is measurable performance, not intuition.

What's next?

Want to know how to adapt SmO₂ to your protocols, workouts or recovery programs?
Do you have another NIRS device and doubt whether it measures what you think it does?

Let's talk. I help you to evaluate it with a scientific and usability vision.

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