Our FYER muscle oxygen sensor comes with: the Train.Red FYER, a charging cable, one Patch Pack (20 patches), and one Strap Pack (S-M-L) all in a durable travel-pouch.
The FYER measures muscle oxygen (SmO2%)
Train.Red tracks your muscle oxygen in real time with sensors. Our smart app translates this muscle data into key features to guide athletes to improve their performance.

FYER SPECIFICATIONS
- Size: 1.2 x 4.4x 5.9 (cm) / .5 x 1.7 x 2.3 (in)
- Weight: 20 grams
- Measure-depth: up to 20mm in your muscle
- Light source & detector distance: up to 35mm
- Sweat-proof: Yes
- Battery: up to 24 hours during active use
- Speed: 10Hz
- Connectivity: BLE and ANT+
- Materials: high-quality biocompatible ABS and TPE
Train.red app
Works best with our Train.Red app. Currently available for Android users. For iOS users we collaborate with VO2 Master (see connectivity). We're working hard on our own Train.Red iOS app providing all data and functionality, we expect to officially release iOS Q4 this year.
Compatability
Compatible with: V02Master Manager, Splendo Health & Fit, ANT+ profile like Garmin, Wahoo, etc. As well as Garmin data field
Train.Red shines a light on your performance based on light technology, the FYER looks inside your muscles with Near InfraRed Spectroscopy (NIRS). The sensor translates the oxygen saturation and (de-)oxyhemoglobin changes in your muscle tissue into real-time key features with the help of artificial intelligence and a friendly user interface.
Our partner Artinis Medical Systems has over 1500 publications, read more publications
Gain strength and/or endurance by using the data from your muscles.
- SmO2%, Muscle Oxygen or Tissue Saturation, is the amount of oxygen in your muscle tissue (%). Adjust your pace in real-time or analyze afterward
- Determine if your muscle is working hard, or hardly working. 5 muscle states are visualized in real-time. Stay in the green state during easy sessions, or go in the red during efforts. Learn more
- High-performance coach or hobby scientist? Measure the Oxy-, and DeOxyhemoglobin concentration changes, or use the total hemoglobin and hemoglobin difference to your advantage.


In Real-time
- Muscle Oxygen: SMO2 percentage and graph (per sensor)
- Muscle States: 5 intensity zones of your muscles
- Pacing: pace yourself with Time In Muscle States feature
- Smart Rest: optimal rest for endurance, hypertrophy and strength
- Muscle Stress Score: amount of muscle stress during your session
the data explained
- SMO2% / TSI%: the percentage of oxygen in your muscle
- 02Hb changes: blood with oxygen (oxyhemoglobin)
- HHb changes: blood without oxygen (deoxyhemoglobin)
- tHb: blood oxygen transport capacity (total hemoglobin)
- HbDiff: the difference between 02Hb and HHb