The most important metric for determining your optimal breathing rate is the relationship between your breathing and your heart rate. “BreathTuner HRV” is, to our knowledge, the only app that can accurately evaluate this correlation and generate a recommendation for your personal best breathing rate. This is possible because “BreathTuner HRV” can simultaneously record your abdominal breathing and also your heartbeats.
The diagrams are copied directly from the app. They each show one breath at different breathing rates.
The green curve is your breathing. As you inhale, the diaphragm moves downward, pushing the abdomen outward (the green curve goes upward). On the exhale, the diaphragm relaxes and the abdomen moves back inward (the green curve goes down). When you inhale, your heart beats faster (red curve up) and when you exhale, your heart beats slower (red curve down). The technical term for this relationship is respiratory sinus arrhythmia. This is a good arrhythmia. With the right breathing rate, you can perfectly synchronize your breathing and your heart, optimizing your autonomic balance and parasympathetic activity.
In the first two images above (breathing speed is 8 and 7 breaths per minute), you can see that your heart is lagging a bit. That is, your heart rate starts to rise or fall a little later relative to your breathing. These breathing rates are too fast for you.
In the last image (breathing speed is 4 breaths per minute), it is exactly the opposite. Your heart is running ahead. Your heart rate begins to rise before the start of inhalation or fall before the start of exhalation. This breathing rate is too slow for you.
In the images in the middle (3rd and fourth image, breathing speed is 6 and 5 breaths per minute), the heart and breathing are well synchronized. That is, your heart rate rises and falls in sync with your abdominal breathing.
BreathTuner can detect, record and evaluate this connection between heart and breathing during a measurement and thus determine your personal best breathing rate.