







Train.Red FYER Muscle Oxygen Sensor + app
Unlock next-level performance with the Train.Red FYER, the most advanced wearable muscle oxygen sensor on the market. While athletes invest in equipment, training plans, and supplements, the true driver of performance is often overlooked: your muscles.
With real-time muscle oxygen (SmO₂%) tracking, FYER helps you optimize training, recovery, and performance like never before. Plus, you can connect 10+ FYER sensors to a single smart device—perfect for team monitoring and group training.
What’s in the box?
✔️ Train.Red FYER sensor
✔️ Charging cable
✔️ Patch Pack (20 adhesive patches)
✔️ Strap Pack (S-M-L sizes)
✔️ Waterproof USB plug
✔️ Durable travel pouch

All you need to know about the FYER
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 USER MANUALSpecifications
- Size: 1.2 x 4.4 x 5.9 cm (0.5 x 1.7 x 2.3 in)
- Weight: 20g
- Measurement depth: Up to 20mm into the muscle
- Light source & detector distance: Up to 35mm
- Waterproof: Yes (swimming possible with added plug)
- Battery life: Up to 20 hours of active use
- Speed: 10Hz
- Connectivity: BLE & ANT+
- IMU: 9-axis motion tracking
- Onboard storage: Your data is always available
- Multi-device connection: Connect 10+ FYER sensors to 1 smart device for team or group monitoring
- Materials: High-quality biocompatible ABS & TPE
Train.Red app
TheTrain.Red FYER works best with ourTrain.Red app, providing in-depth muscle oxygen insights to help you train smarter.
📖 Check the app manual here.
Compatibility
✔️ VO2Master Manager
✔️ Splendo Health & Fit
✔️ ANT+ profiles (Garmin, Wahoo, etc.)
✔️ Garmin Data Field Integration
✔️ Fulgaz, and more
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