I’ve begun to read this book – and am currently around half way through. There is one part that I keep coming back to (which is also why I’m writing this) as it has really stood out to me and something that I want to engrain in my mind. I’m a big believer in coherent / resonant breathing. My own experience leads me to know that when I breathe in a rhythm of 6 seconds for an inhale / exhale I immediately feel so much better. Physically my body feels relaxed and calm, which in turn is reflected in my mental state. However sympathetically driven / unregulated / stressed / anxious / tired / overwhelmed I may feel within 3 rounds of breathing in this way it completely changes my state of being.
Where the book has been instructive is in looking at what the authors believe happen at this cadence of breathing, this specific cadence of breathing (which for them, to be exact is 58 seconds for a round of 6 breaths, is just under 6 seconds an inhale. One of the key drivers from this is covered on page 17-18 where the relationship between arterial pressure, heart rate variability (so heart rate) and breathing is covered.
The author starts: “the cardiopulmonary system, including of central nervous system aspects, takes its cue from the breathing rate, ie the faster the breathing cycle, the faster the average heartbeat rate and the lower the heart rate variability amplitude. In this regard the autonomic nervous system while at rest is very similar to its behaviour during exercise” so nothing groundbreaking here – more an establishment of the order, or capability and leverage that breathing can have over our physiology.
The next sentence is key in where this can lead: “Instantaneous arterial pressure [blood pressure] follows respiration resulting in a phenomenon known as the ‘repsiratory arterial pressure wave’ . . . when HRV amplitude is high, instantaneous pressure follows respiration, arterial pressure and heart rate variability cycles varying by 180 degrees” so this really piqued my interest and I wanted to know why and what this meant for us. The author then explains the mechanics of this:
- When we inhale we create a strong negative thoracic pressure, leading to the lungs expanding and air begin drawn into them. (pressure forcing air to flow from high to low)
- This internal pressure differntial also causes the blood vessels in the chest to expand, which leads to storage of blood in the chest during inhalation which reduces the return of blood to the heart.
- Heart output is lowered – arterial blood pressure is lowered
- The opposite is true for exhalation, diapraghm ascends, positive thoracic pressure leads to a deflation of the lungs as air is emptied
- Blood vessels in the chest contract, reducing the storage of blood in the chest
- Heart put is increased leading to an increase in arterial blood pressure.
So in an ideal world as we inhale, heart rate increases, yet arterial pressure falls and vice versa (leading to the 180 degree opposite cycle). The author then goes on to extrapolate what this leads to:
“From this we see that breathing plays a key part in moving the blood. It appears that when breathing is relatively fast, shallow and asynchronous, the heart effectively bears the burden of generating and sustaining blood pressure, and for this reason, arterial pressure aligns with the HRV cycle. As the breathing becomes slower and deeper, the mechanical action of breathing itself takes on a grater and greater role in moving the blood. And, as a consequence, heart rate increases dramatically during inhalation and decreases dramatically during exhalation. Note that if the heart rate did not increase and decrease accordingly, arterial pressure would fall and rise excessively. In this way, the HRV cycle plays a key role in moderating the respiratory arterial pressure wave. Building on this understanding, what would the consequence be of very low HRV amplitude, ie the heart bearing the burden of generating and sustaining blood pressure?”
The next page then explains the authors answer, that of hyper tension. This seen as a sympathetic condition, where our breathing is too rapid and or shallow to allow the HRV necessary, that helps the body naturally move blood at a more optimal pressure and therefore work more effectively and in a more healthy fashion.
This really sticks out for me in how we can manage hyper tension.
Slower breathing, at a greater depth, allows for the natural swing from inhale to exhale,
From pressure rise to pressure fall.
Blood expands, heart rate output falls, arterial pressure falls as heart rate rises.
Blood contracts, heart rate output rises, arterial pressure rises, heart rate falls.
Without this balance, this breathing cadence, the system is then hijacked by the sympathetic dominated side and the heart kicks in to take ownership, thus over-riding the normal balance that is safer.
Over time, chronically this then becomes hyper tension. Which also shows just how important & valuable it is to use your breathing to reset this relationship.
The next chapter (for next week) then goes into more detail as to why the resonance of 6 / 6 is so effective (as why not 5/5 or 8/8?)