Discover the Power of Data with our Revolutionary Muscle Oxygen Sensor.

quick start

  • Unpack sensor
  • Install app
  • Attach & connect sensor
  • Ready to go



Your package contains the following items:

You will also need:

Train.Red app (or use one of our connectivities)



  • Use the included charging cable
  • Insert the charging cable with care
  • The green LED is blinking slowly while charging
  • The PLUS is fully charged when the green LED stops blinking.
  • You can measure up to 6 hours on a full charge.
  • A full charge takes up to 2 hours
  • The PLUS resets when you plug in the charging cable.


  • Make sure you're charged (you, and your battery).
  • Press the start button to activate the sensor.
  • After the start sequence, the green LED is on and the blue LED is blinking. This indicates that the sensor is ready to connect.
  • The green LED blinks when the sensor is connected to software (e.g. the APP), and the solid blue or purple LED shows it is connected via Bluetooth or ANT+.
  • When you are not connecting the sensor to the APP, it shall shut down automatically.
Train.Patch - 20 pack


The FYER can be worn everywhere on your body and the app currently saves 8 locations. Select and connect your sensor in the 'connect sensor' section of the smartphone app. You can connect up to 4 Fyer's and 1 HR sensor at once.

How to strap the sensor:
- Choose the right strap length
- Position the sensor directly on your skin, and place it on the belly of your muscle for maximal results.
- Pull the strap nice and tight, but do not compress your skin.
- OPTIONAL: Standardise placement and protect from ambient light with the Train.Red patch (*do not use if you're allergic to physiotape)
- Check your sensor placement with our position check in the app

Note: never place your sensor over a tattooed area


  • Select your type of sport and workout
  • Make sure you selected and positioned the desired sensors
  • Start measurement via the play button
  • Wait until sensors are connected
  • App switches to the live-measurement overview (an overview of data and features)
  • By tapping the feature, the user can enlarge the desired feature.
  • Go and be ahead
  • Press the stop button if you want to stop recording
  • The app shows a quick summary of your training


Currently, we are still working on some of the desired features. For now, you can view a summary of each training via the app. If you want to analyze your sessions, you can also export the training to a FIT or CSV file:

  • Muscle oxygen data
  • Muscle states
  • TSI% (percentage of available oxygen in your muscles)
  • Oxy and deoxyhemoglobin changes
  • HbDiff (difference between oxy and deOxy hemoglobin)
  • Total hemoglobin

    And some extra information e.g. battery status, temperature data, time stamps and BLE quality.


Clean the sensor by using a soft cloth, moistened with a non-aggressive general purpose cleaner (e.g., alcohol). Do not spill any liquid onto the instrument.