new Train.Red PLUS Launched – MOXY-beater?

train-red fyer and plus
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new Train.Red PLUS Launched – A MOXY-beater?

I’ve been using the TRAIN.RED muscle oxygen sensor for several weeks now and was expecting a new, improved version to be launched. Well, it was…yesterday.

I have the existing Train.Red FYER sensor and that is probably on a similar level to Moxy Monitor in terms of accuracy (although the products differ in how they get to similar levels of accuracy). However the new Train.Red PLUS sensor is deemed to be a further improvement.

I’ll be covering Train.Red to some degree in the weeks ahead but here are some takeouts now on the new sensor and why it might be a Moxy-beater.

Benefits of Train.Red PLUS

  • Signal penetrates further into muscle tissue and hence it ‘measures deeper’
  • Faster in the sense that the PLUS model has 100Hz data. the FYER model is 10Hz and Moxy runs lower still
  • Light, small and easily wearable during sport

Train.Red PLUS Specifications

  • Size: 1.5 x 4.4 x 6.8 (cm) / 0.6 x 1.7 x 2.7 (in)
  • Measure-depth: up to 40mm in your muscle
  • Light source & detector distance: up to 40mm
  • Sweat-proof: Yes
  • Battery: up to 24 hours during active use
  • Speed: 100Hz
  • Connectivity: BLE and ANT+
  • IMU: h9-axis inertial measurement unit
  • Compatible with: V02Master Manager, Splendo Health & Fit, ANT+ profile, Bike computers like Garmin & Wahoo. As well as a Garmin CIQ data field. (It also works with other vendors’ SMO2 CIQ data fields too)

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Some scientific Studies include

One study here shows Moxy is accurate. The PortaMon product is a more widely tested product made by Artinis Medical Systems. You might think its wider tested base makes it more of a gold standard. But let’s put that to one side. The next generation of PortaMon will include the same sensor that’s in the Train.Red PLUS product. So, draw your own conclusions from that!

  • Ferrari et al. (2012) compared the PortaMon to an invasive technique for measuring muscle oxygenation in a group of elite cross-country skiers. They found that the PortaMon was highly correlated with the invasive technique and was a valid and reliable tool for monitoring muscle oxygenation during exercise.
  • Wehbe et al. (2015) compared the PortaMon to another commercially available muscle oxygen sensor and found that both devices provided similar measurements of muscle oxygenation during cycling exercise.
  • Kounalakis et al. (2019) evaluated the accuracy of the PortaMon during a range of cycling intensities and found that the device was highly accurate and reliable for measuring muscle oxygenation.
  • A study by Hamaoka et al. (2011) compared the Moxy Monitor to an invasive technique for measuring muscle oxygenation and found that the Moxy Monitor was highly correlated with the invasive technique and was a reliable tool for monitoring muscle oxygenation during exercise.
  • A study by Van Beekvelt et al. (2001) evaluated the reliability of the PortaMon in measuring muscle oxygenation during different levels of exercise intensity and found that the device was highly reliable and consistent in its measurements.


The Muscle Oxygen sensor market is divided into sports labs and consumers. The latter are typically highly motivated and knowledgeable self-taught athletes. There is a potentially much wider market for SMO2, but it remains largely untapped for a variety of reasons that I will cover in later content.

Train.Red’s new PLUS sensor may well beat Moxy in lab setups, but it can be challenging to displace an accepted incumbent. If it demonstrates superior technical abilities, especially in terms of accuracy, you would expect it to eventually become the market leader. Assuming, of course, that Moxy does nothing, which is unlikely.

From a self-taught/committed athlete’s perspective, I like the wearability of Train.Red. It is usable in a more controlled home pain cave environment where you might have multiple data viewers. However, when used on the road, it effectively requires an Android phone. An Apple Watch app or an improved Garmin CIQ data field would improve its usability for real-time pacing. Failing that, if Garmin or Wahoo can improve their standard SMO2 metrics to show muscle states, it would considerably improve the usability of SM02 in general, but I doubt it will happen.



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5 thoughts on “new Train.Red PLUS Launched – MOXY-beater?

  1. On a somewhat related note, have you noticed Garmin connect stopped graphing the smo2 values recorded using the native smo2 sensor type?
    I was using that with my humon hex, rather than taking up a ciq slot with the custom field.

    1. hmm
      no i hadnt
      thats a pita
      i had noticed that connect had stopped showing the colour coded Humon Hex data. I just assumed that was because i had an old ciq on a new watch

      1. I raised a support ticket with Garmin but couldn’t make the T1 support person understand the issue. They kept saying that it was a 3rd part sensor and this not their problem, but the data is in the fit file, put their by their own datafield….
        Maybe you could have more luck.

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