After reading James Nestor's Breath, I went through the Oxygen Advantage certification for fun. Lots of studies that show that the 4/6 or 5/5 cadence (ten secon

After reading James Nestor's Breath, I went through the Oxygen Advantage certification for fun. Lots of studies that show that the 4/6 or 5/5 cadence (ten second round trip, leading to six breaths a minute) strongly improves heart rate variability and engages the parasympathetic nervous system. OP had a cool idea -- wish it hit the 5/5 cadence.