BREATHING AND THE RESONANT FREQUENCY

HRV Biofeedback requires to breathe at low frequencies (deep breathing), which stimulates parasympathetic activity. Experimental studies have found the highest amplitudes in instantaneous heart rate oscillations when breathing at approximately 0.1 Hz. This means 6 breaths per minute and is the default in the app

However, the frequency at which amplitude is maximal for a person can be slightly different.  This is what is called the resonant frequency and can vary by up to 2 breath/minute between people

Your resonant frequency can be established with a protocol that consists of breathing at different frequencies for a few minutes until the frequency that elicits the maximal amplitude is found

You can do so in the HRV4Biofeedback app, from the Breathing menu. The test will last 6 minutes and works as follows:

• The guided breathing will change over time during the 6 minutes, going from 7.5 to 5 breaths / minute
• You should try to follow the pacer for the entire duration of the test, which is very  similar to a regular session, but with the main difference that the breathing frequency will automatically change
• Another small difference is that this time the timer will show a count down, starting from 6 minutes. Once the test is finished, the app will automatically stop the measurement and compute your resonant frequency, as shown in the screenshots below
• You will also be able to see the heart rate trace for the entire recording, which normally shows larger oscillations as you do deeper breaths towards the second half of the test

While the resonant frequency test should find the optimal breathing frequency for you, you might feel more at ease with a slightly different breathing rate. Feel free to always change the breathing rate using the slider in the Breathing page, the app will use your configuration for the following sessions