HeartBreath HRV App Reviews

After watching some podcasts on respiratory sinus arrhythmia by Richard Gevertz (sp?) I’ve been trying to figure out how to measure it. This works. You can see a huge difference in the readings and graph when you breathe the timed breathing versus breathing normally. I wish there was more explanation of how to tell if you have the best breathing pace, I guess it’s just experimentation, but there is no clear cut guide I could find on the best way to use this app so I’m sort of figuring it out m