Dr. Andy Galpin

And you'll be stunned, stunned on aggregate in large populations. Mood is a very strong predictor of overall nervous system state. How tired are you? So fatigue is another question. One we see often is called RPE, so rate of perceived exertion. Just different ways to ask about how do you feel today? What's your effort feel like today? How interested in training are you today?

Tons of different questions there. That's hedged more towards your subjective experience where the previous ones are obviously looking at objective performance, but there is classic overlap between both of them.

Tons of different questions there. That's hedged more towards your subjective experience where the previous ones are obviously looking at objective performance, but there is classic overlap between both of them.

The third one though that is more objective and where the bulk of the published research is, which doesn't mean they're better by the way, it just means they're used more scientifically, are in what I call the physiological markers. Common ones here are blood tests. I've spoke in season one. We had an entire episode on overtraining and overreaching.

The third one though that is more objective and where the bulk of the published research is, which doesn't mean they're better by the way, it just means they're used more scientifically, are in what I call the physiological markers. Common ones here are blood tests. I've spoke in season one. We had an entire episode on overtraining and overreaching.

We also had one on how to interpret blood tests for high performance. In both of those, I talked about a number of different blood and salivary markers you can use to assess overall fatigue and readiness and performance. We'll have direct links to those episodes in the show notes. You can go check them out and see what I'm talking about.

We also had one on how to interpret blood tests for high performance. In both of those, I talked about a number of different blood and salivary markers you can use to assess overall fatigue and readiness and performance. We'll have direct links to those episodes in the show notes. You can go check them out and see what I'm talking about.

But we're not going to get into that stuff today because we've covered a lot of it already. What we will get into for the most part are what I call the respiratory physiology markers. This is everything from resting heart rate to something called your heart rate variability or HRV to respiratory rate and CO2 tolerance. HRV, heart rate variability, is the king here.

But we're not going to get into that stuff today because we've covered a lot of it already. What we will get into for the most part are what I call the respiratory physiology markers. This is everything from resting heart rate to something called your heart rate variability or HRV to respiratory rate and CO2 tolerance. HRV, heart rate variability, is the king here.

Not saying it's the best, but it has the overwhelming majority of the research is on HRV. You don't see a lot anymore on resting heart rate, and that's because it's not very sensitive. We used to look at it a little bit more and we kind of walked away from it.

Not saying it's the best, but it has the overwhelming majority of the research is on HRV. You don't see a lot anymore on resting heart rate, and that's because it's not very sensitive. We used to look at it a little bit more and we kind of walked away from it.

If you get really shot for a long time, you're over-trained or highly chronically stressed or have a chronic disease, you will start to see increases in resting heart rates that are not being explained by a lack of physical fitness or cardiovascular fitness.

If you get really shot for a long time, you're over-trained or highly chronically stressed or have a chronic disease, you will start to see increases in resting heart rates that are not being explained by a lack of physical fitness or cardiovascular fitness.

So you can see changes in heart rate as a result of this autonomic nervous system being pushed into a direction, in this case, more sympathetic than you'd like. but it takes a long time. You're not gonna see the resting heart rate move for several weeks before you would really notice. And then the amount of movement is small. So it's hard to understand kind of signal to noise ratio there.

So you can see changes in heart rate as a result of this autonomic nervous system being pushed into a direction, in this case, more sympathetic than you'd like. but it takes a long time. You're not gonna see the resting heart rate move for several weeks before you would really notice. And then the amount of movement is small. So it's hard to understand kind of signal to noise ratio there.

So honestly kind of cross off resting heart rate, not a great marker. I don't know too many people that use it by itself or certainly use it as their first line of measurement. Now, heart rate variability is much more documented. Respiratory rate is growing. That's something we're learning much more about.

So honestly kind of cross off resting heart rate, not a great marker. I don't know too many people that use it by itself or certainly use it as their first line of measurement. Now, heart rate variability is much more documented. Respiratory rate is growing. That's something we're learning much more about.

And CO2 tolerance is something that I have used a lot, but there's not a ton of research behind that either. I will share with you my personal experiences with all these things, but I want to spend most of our attention today on HRV because we have so much more information to go off of. So let's dive into HRV. What is it? Why do you care? And how do we manipulate it?

And CO2 tolerance is something that I have used a lot, but there's not a ton of research behind that either. I will share with you my personal experiences with all these things, but I want to spend most of our attention today on HRV because we have so much more information to go off of. So let's dive into HRV. What is it? Why do you care? And how do we manipulate it?

Heart rate variability is exactly what it sounds like. It is the variation in your heart rate. Let me use an example. Let's say your resting heart rate is 60 beats per minute. You would then assume that since there's 60 seconds in one minute, that your heart is then beating, in this example, every second on the second.