BreathTuner HRV

BreathTuner HRV offers you the possibility to find out your individual breath resonance frequency by means of several measurements. When you breathe at your own personal respiration / breathing rate, your heartbeat speeds up during inhalation and slows down during exhalation. This is also called coherent breathing or RFB = resonant frequency breathing. (From a medical/physiological point of view, this phenomenon is caused by the RSA = respiratory sinus arrhythmia).

The App BreathTuner HRV provides various breathing programs for this purpose. These programs guide you through a sequence of different breathing frequencies with which you should breathe for 1 to 2 minutes. After that there is a break of about 20 – 60 seconds. You should do this process sitting upright.

About breathing

Breathe through the nose whenever possible. However, exhalation can also be done through the slightly open mouth, aka “pursed lips breathing”. You breathe mainly down toward the abdomen (diaphragmatic breathing) and less into the chest during the whole process. It should be a natural to slightly deepened breathing with neither too much nor too little air.

There are two general ways to take your pulse.

Pulse measurement with camera

One way to measure your pulse is to gently place a finger on the iPhone camera and flash light (setting: “Use camera”). This measures the blood flow in the finger from the camera and the flash. Please always use the top lens on your camera system.

For the measurement of the belly breathing we recommend to put a pad on your lap and the iPhone on top of it, with the lower edge against your belly (see the following pictures below).

The bottom edge of the iPhone against the abdomen when measuring the pulse with the camera system.

Pulse measurement with chest strap

Even more accurate results are obtained when using the chest strap Polar H10, because it provides a high quality ECG signal, which is analyzed accurately by BreathTuner (setting: “Use HR-Monitor”). Besides the “Polar H10”, the chest strap models “Polar H7” and “Garmin HRM-Dual” can be used optionally. However, the H10 is the most suitable because of the ECG function.

When using a compatible chest strap, place the iPhone on the abdomen below the navel, or even better, put it in the waistband of your pants, which is loosened slightly beforehand. The screen must face away from the abdomen – just like in the VaYou app.

Positioning of the iPhone on the abdomen when using a chest strap like Polar for pulse measurement.

Tips for a good result

  • Choose a good time: in the morning or during a break. A BreathTuner breathing program actually makes a good break program. Not ideal is right after a meal or coffee, or right after a workout. Also not if you feel overtired.
  • breathe through the nose whenever possible.
  • choose a seat that is as comfortable as possible, where the back can be reasonably upright and relaxed. If you always use the same sitting situation for the measurements, this is of course ideal.
  • tip for newcomers: if someone has never breathed with guided/paced breathing before, it is advisable to use the first runs for practice and rather discard the measurement results. Especially very slow breathing rates are quite unusual for beginners and need some practice. This will also improve the measurement results significantly.

Time sequence of a measurement

  • For chest strap: First, it’s best to put on the H10 and turn on Bluetooth (your chest strap must be paired with your phone once in the settings under “Use HR monitor”).
  • Then go to settings and find a breathing sound you like best. You can also activate spoken instructions. Breathing sounds convey in an acoustic way how and when you should first inhale and then exhale.
  • Then select, for example, the first breathing program “8-7-6-5-4” or better trust the automatic program selection of the software.
  • Tap the button at the bottom left for “Measurement”. To start the breathing program tap on the blue symbol in the upper center.
  • Then position the iPhone as described above. If you don’t use a chest strap and have activated the option “Use camera”, also place a finger gently over the camera and flash light. Now just breathe relaxed and follow the spoken instructions.
  • It is recommended to keep your eyes closed during the whole process, if this is relaxing for you. Otherwise, let your gaze rest. During the pauses you can take your finger off the camera.
  • The breathing program is relaxing, almost meditative, and lasts about 15 minutes in total. You only need to follow the spoken instructions.
  • At the end, the display shows an overview of the individual sections with an indication of the breathing frequency of this recording that tends to be the most suitable for you personally.
  • Now please rate the breathing segments. For which breathing segments did you feel better or worse? This is important for the automatic evaluation.

The “Review” page shows an overview of all your recordings/measurements including ratings, details and a recommendation regarding your personal breath-heart resonance frequency.

BreathTuner “Review” page

Measurement series

For the most accurate determination of your individual breathing resonance frequency, BreathTuner guides you through a series of measurements at different breathing rates. Alternatively, it is also possible to select individual breathing programs. For the most neutral result possible, you should only take one measurement at a time and not several in a row.

  • Basic: You start with at least two measurements from the “Basic” category. The software can make a rough estimate of your best breathing rate (with a resolution of approx. 1 breath / min.).
  • Advanced: Depending on the results of the “Basic” measurements, you should then make at least two recordings from the “Advanced” category to determine your individual resonance frequency with an accuracy of about 0.5 breaths / min.
  • Pro: Depending on the results of the “Basic” and “Advanced” measurements, you can then take at least two measurements from the “Pro” category to determine your personal best breathing rate with an accuracy of approx. 0.25 breaths / min.

After performing the entire series of measurements, it is possible to determine your individual breath-heart-resonance frequency with an accuracy of 0.25 breaths/minute.

Review / Details

The Details page (right top in Review) and separate details pages for every single session (click in the session list) provide access to diagrams and analysis parameters.

The Details page combines parameters from selected recordings for an estimation of the resonance frequency

Details for Professionals

All coherence values are calculated for the entire duration of the measurement per respiratory rate (i.e. 2 minutes minus 3 seconds each at the beginning and end of the measurement). For the calculation of the common HRV parameters (SDNN, RMSSD, pNN50, LF, HF etc.) the first two breaths of each breathing section are currently ignored. In addition to the “Polar H10” the Bluetooth chest strap models “Polar H7” and “Garmin HRM-Dual” can be used for measurements. For any questions, wishes and suggestions please contact

A scientific article related to the resonance frequency topic can be found here.

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