OXYGEN & CARBON DIOXIDE
You may hear people talk about “oxygenation” of the blood through deep breathing, but that is not really what happens. Due to something called the (nerd alert!) oxygen-hemoglobin dissociation curve, it is next to impossible to change the amount of oxygen in our tissues in any meaningful way. Hemoglobin—the protein that carries oxygen in the blood—holds on tighter to oxygen when there is less coming in through the lungs. When there is lots of oxygen coming in, the hemoglobin allows it to come and go freely. This results in a steady supply of oxygen to the cells and tissues of the body, regardless of how much we breathe.
The real chemical element that changes when we do breathing exercises is carbon dioxide. When we breathe more than normal, we expel lots of carbon dioxide from our system, changing the chemistry of the blood. Less carbon dioxide makes the blood alkaline, resulting in a cascade of secondary effects in our nervous system, lungs and brain. We often feel it as “light-headedness.”
When we breathe less than normal—the ultimate goal of yogic pranayama practice—carbon dioxide builds up in our blood, making it acidic. This creates a similar but opposite cascade of effects in the nervous system, lungs and brain. It causes dilation of the vessels in the brain and the desensitization of the peripheral nervous system. We feel it as a calm (or even numb) body and an alert mind. Does that sound like meditation to anyone?
Once we are aware of the effects of our breathing on our brain, we start to control it. This is when we enter Level 3, where the true practice of Pranayama begins.
