Basic Breath Physiology & Biomechanics

Getting to the heart + lungs + diaphragm of the matter

Chapter 4 is a great review for me, and I certainly learned a few things, too.

There’s one key theme that Jill covers early in the chapter that I still need some help unpacking (I plan to ask her in our Q&A). It’s the section about CO2. On p. 99, she talks about her own lightbulb moment in 2003, when she heard Roger Cole say the following:

Pranayama (breathing exercises) are designed not to increase your oxygen levels — those are fairly constant — but rather to increase your capacity to tolerate CO2.”

Cole goes on to describe that higher CO2 thresholds help us induce the relaxation response that give us that “yogic high.”

The takeaway is that our aim with breath-work is to “help your body become better equipped to tolerate CO2 and use your breath as a tool to improve your parasympathetic capacity.”

I’m going to look at the QR codes on pp. 98-99 (Bohr Effect and Huberman Lab), because this minutiae of increasing CO2 tolerance is still a bit of a head-scratcher for me.

I sailed with excitement through the rest of the chapter, though, where she teaches about the three zones of respiration. I thought it was interesting to learn the why behind the different zones. She states it a number of different ways, and very succinctly on p. 103: