Train.Red Looks at my attempt at a Wahoo 4DP Test
More: detailed Train Red Review – FYER & Plus
As part of my look at several of the Muscle Oxygen Sensors this year, Train.Red kindly offered to analyse my Wahoo 4DP Test (formerly from Sufferfest). This is an extremely hard test if done properly and it assesses the strength and weakness of your ability to produce power for different durations – hence all energy production systems are tested in 60 minutes of unpleasantness!
Why Train.Red?
- It uses a current-generation gold standard sensor from Artinis.
- It takes deeper, more frequent readings than other sensors – you can see individual muscle contractions
- Live Muscle ‘states’ are reported (Like supersapiens glucose, SmO2 does not have zones)
- When cycling, 300w now is not the same as 300w in 60 minutes. Even if you took into consideration W’, I would expect that Muscle Oxygen states better reflect your ability to perform as that workout continues. (FTP tests tend to overestimate MLSS) More: science stuff from Jem Arnold
- Supports: Garmin data fields, ANT+ compatibility with Muscle Oxygen Profile (Wahoo, Garmin), Bluetooth link to smartphones and web platforms.
Issues
Train.Red’s app has been evolving significantly over the last few months and is now in a good place with significant new features released and a few more to follow. The Garmin CIQ data field works but needs enhancement.
SmO2 readings can vary depending on sensor placement. I like Moxy’s shorts that have an inbuilt, fixed position on the quads for its sensor. Or put another way, I moved the Train.Red sensor during the test 🙂
Thierry at Train.Red helpfully told me to try harder next time! He also commented about my inability to correctly perform the last 1-minute part of the due to muscle exhaustion might mean that the test does not correctly determine anaerobic capacity. I seem to recall that Wahoo/Sufferfest tried to take this into account in the design and interpretation of the test.
https://the5krunner.com/2023/10/18/nnoxx-one-analysis-running-cycling/
Last Updated on 27 January 2026 by the5krunner
My favourite kit and nutrition
- Injinji – Runners protect your toes. Avoid discomfort and minor injury. Run more. run faster. I use them.
- Garmin 90-degree charging adapter — the small adapter that keeps your charging cables tidy. Essential for race day. I use one.
- Garmin charging puck — the fastest and most reliable way to top up your Garmin before a session. I use one.
- Ravemen FR300 — front light that mounts directly under your Garmin or Wahoo head unit. Keeps your bars clean and your beam pointed where it matters. I use one.
- Body Glide – The Blue anti-chafe stick that all swimmers and many runners use. I use it.
- Maurten — the race nutrition trusted by elite athletes. Gels and drink mix engineered to be easy on the stomach. I use them.
- Garmin Varia RTL515 — radar rear light that alerts you to vehicles approaching from behind. Pairs with your Edge or Garmin watch. I use this model.
- Favero Assioma Pro RS2 — the power meter pedals most serious cyclists end up choosing. Accurate, easy to move between bikes. I use this model.
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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
