Dr. Andy Galpin

And the way that this works is it's effectively like a little bit of a breath hold test where you exhale continuously and you can see how long that you can continually exhale some small amount of air. It's a maximal effort test. In the show notes, we'll put a direct link to a video Brian has made that shows you how to go through the CO2 tolerance test. And I like it. We've used it a bunch.

I also feel like it tells us something similar, but slightly different than both HRV and respiratory rate. So while I told you earlier, we look at both of those, we also look at CO2 as much as we can. I can't get CO2 tolerance though from a simple test on a resting test. You actually have to actively do it. It only takes about a minute.

I also feel like it tells us something similar, but slightly different than both HRV and respiratory rate. So while I told you earlier, we look at both of those, we also look at CO2 as much as we can. I can't get CO2 tolerance though from a simple test on a resting test. You actually have to actively do it. It only takes about a minute.

But because of that, people won't necessarily do it every day where I can check their heart rate easily, whether they're doing something or not. So that's the only reason why we don't use it necessarily every day. But here's the connection. The way that your physiology works is you will bring in oxygen when you take a breath in.

But because of that, people won't necessarily do it every day where I can check their heart rate easily, whether they're doing something or not. So that's the only reason why we don't use it necessarily every day. But here's the connection. The way that your physiology works is you will bring in oxygen when you take a breath in.

And you're doing that because oxygen's primary job is to regulate metabolism. It's energy production, right? It's aerobic metabolism, which is what most of your body's doing most of the time. When you breathe out, you're breathing out CO2. The difference between oxygen and CO2 is that carbon molecule. That carbon is a byproduct of any metabolic process.

And you're doing that because oxygen's primary job is to regulate metabolism. It's energy production, right? It's aerobic metabolism, which is what most of your body's doing most of the time. When you breathe out, you're breathing out CO2. The difference between oxygen and CO2 is that carbon molecule. That carbon is a byproduct of any metabolic process.

So whether you're breaking down carbohydrates or fat, whether you're using that resulting energy for exercise or digestion or immune function or cognitive performance, it doesn't actually matter. It all is going to net result in you leaving a little bit of the water leftover, making some ATP, and having a bunch of free-floating carbon. That carbon in your system is highly problematic.

So whether you're breaking down carbohydrates or fat, whether you're using that resulting energy for exercise or digestion or immune function or cognitive performance, it doesn't actually matter. It all is going to net result in you leaving a little bit of the water leftover, making some ATP, and having a bunch of free-floating carbon. That carbon in your system is highly problematic.

And so your body will immediately attach it to an oxygen molecule forming CO2. And so the way we say this is the net end result of all metabolic processes are water, ATP, and CO2. Now, if you're in the case of, let's just say exercise, it doesn't matter, but let's just say we are doing that, the more metabolism you go through, the more CO2 is generated in your muscle.

And so your body will immediately attach it to an oxygen molecule forming CO2. And so the way we say this is the net end result of all metabolic processes are water, ATP, and CO2. Now, if you're in the case of, let's just say exercise, it doesn't matter, but let's just say we are doing that, the more metabolism you go through, the more CO2 is generated in your muscle.

Your muscle then puts it into your blood and then transmits through your blood, goes into your lungs, and then you exhale and get it out. That's the entire cycle of life. Plants do the opposite. They breathe in CO2, pull out the carbon, keep it, hold on it to themselves, and then get rid of the O2, right? That's the relationship living beings have with plants in terms of oxygen and CO2.

Your muscle then puts it into your blood and then transmits through your blood, goes into your lungs, and then you exhale and get it out. That's the entire cycle of life. Plants do the opposite. They breathe in CO2, pull out the carbon, keep it, hold on it to themselves, and then get rid of the O2, right? That's the relationship living beings have with plants in terms of oxygen and CO2.

Why this matters, again, you breathe in oxygen to regulate metabolism, but your CO2 levels are there to regulate your pH. It has nothing to do with your exercise performance. Your body will regulate blood pressure, it will regulate electrolytes, and it will regulate pH over almost anything. And one could argue it will regulate pH literally over anything else in the whole world.

Why this matters, again, you breathe in oxygen to regulate metabolism, but your CO2 levels are there to regulate your pH. It has nothing to do with your exercise performance. Your body will regulate blood pressure, it will regulate electrolytes, and it will regulate pH over almost anything. And one could argue it will regulate pH literally over anything else in the whole world.

That is because most of your body, the vast majority of all enzymes in the world, have to run at a very specific pH. Too acidic or too alkaline, they don't work. If they don't work and your heart can't pump and your brain can't operate, you die pretty quickly. So your physiological pH levels are maintained at an incredibly tight number. Your testosterone can easily triple in a few minutes.

That is because most of your body, the vast majority of all enzymes in the world, have to run at a very specific pH. Too acidic or too alkaline, they don't work. If they don't work and your heart can't pump and your brain can't operate, you die pretty quickly. So your physiological pH levels are maintained at an incredibly tight number. Your testosterone can easily triple in a few minutes.

Your adrenaline can go up many multiples. Your pH stays within an extremely tight window. It will move everything else around it to keep your pH at the right level. The primary way your body regulates your pH is by changing the amount of CO2 that it lets be in your blood. If CO2 levels get too high in your blood, This will tell your autonomic nervous system to breathe more. You don't feel it.

Your adrenaline can go up many multiples. Your pH stays within an extremely tight window. It will move everything else around it to keep your pH at the right level. The primary way your body regulates your pH is by changing the amount of CO2 that it lets be in your blood. If CO2 levels get too high in your blood, This will tell your autonomic nervous system to breathe more. You don't feel it.

This is subconscious. You're just breathing more. You have no idea what's happening. Not an active process, autonomic nervous system. It does that, it gets rid of the CO2, it brings the acidic level down. If the acidic level is too low, meaning you're too alkaline, it will have you slow your respiration down. You'll hold your breath. Again, you won't even know this.