new Train.Red PLUS Launched – A MOXY-beater?
Update, September 2026: this launch post describes the first-generation PLUS, and its specifications are out of date. The current PLUS 2.0 measures up to 25 mm deep and runs for up to 20 hours. See my Train Red review for current specifications, prices, FYER 2.0 and the new FYER PRO.
More: detailed Train Red Review – FYER & Plus
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 FYER 2.0, FYER PRO and PLUS 2.0
Muscle oxygen (SmO2) sensors for Garmin, Wahoo and Suunto. 10% off with code THE5KRUNNER.
Direct from Train RedValidation
Moxy’s published validation includes a 2019 study of the reliability and validity of its 0-100% scale. Train Red’s sensors come from Artinis Medical Systems, whose laboratory PortaMon has been used in research for many years, and Train Red lists the studies that have used its own sensors on its publications page. For an overview of how muscle oximetry is used in sport, see the 2024 systematic review in Sports Medicine by Perrey, Quaresima and Ferrari, and my muscle oxygen sensors guide.
Thoughts
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. 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.
More: https://train.red
Related reading: Garmin CIQ Data Fields on Watches No Longer Fit For Pur….
Last Updated on 23 September 2026 by the5krunner
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tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors. ID
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.
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
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.
maybe they dont have the ‘markup’ (or whatever its called) to make it display the data properly ?????
hi,
according to the Train Red website the PLUS goes up to 25 mm, the article mentions up to 40 mm