On Optimal Biofeedback Parameters for Heart Rate Variability Improvement Using Breathing Entrainment

Slow breathing techniques and breathing entrainment represent promising approaches to stress reduction, autonomous nervous system improvement and improved cognitive function. The most frequently used techniques use predefined breathing rates and the resonant characteristic of heart rate variability at ~0.1Hz, the frequency of the blood control loop. We present a new method of evaluation of the personal resonant breathing frequency for the maximum heart rate variability and implementation of a real-time breathing entrainment system that automatically adjusts to the current optimal breathing frequency of the user. We demonstrate the existence of the personal optimal breathing rate, and demonstrate the change of the optimal breathing rate during the session. In our pilot experiment, we found that the magnitude of the respiratory sinus arrhythmia (RSAM) represents a promising parameter for optimization of the breathing entrainment rate, and demonstrated increase of RSAM power by continuous tracking of the optimal personal breathing rate from 100 ms
$^\wedge 2$
to more than 500 ms
$^\wedge 2$
.