Dr. Rhonda Patrick: Since we're talking about vigorous intensity and adding more of a stressor and a stronger stimulus, maybe you can recap some of what Dr. Benjamin Levine, Dr. Martin Gibala talked about on the podcast when they were sort of defining the various training zones and what these zones are, because there is a lot of information out there on that, which can be quite confusing to people.

Brady Holmer: It can be. And some people will like to use zones for training. I think it's common in sort of the exercise with, you know, coaches who are coaching endurance athletes to use this 5-zone model. If people, you know, are familiar with listening to podcasts on fitness, they'll probably hear people reference 5 zones. There are obviously other zones to use, but yeah, Dr. Benjamin Levine defined these sort of 5 training zones.

And kind of before I go and define what these are and how people can use them to guide their training, I think it's He kind of defined them using 3 different metrics and that we're gonna use to define each of the zones. But lactate levels are one way to do it, but we're not really gonna discuss that because in reality, you know, most people are not gonna be measuring their lactate levels weekly, monthly, or even, you know, certainly not daily during exercise. And so it's kind of a moot point to say, you know, zone 2 exercise is this lactate level. Most people don't really know what that is. And so there are other ways to measure intensities and use these zones. One way is just your rating of perceived exertion or RPE.

Um, and this is just a subjective measure of how hard you think you're exercising. And this is typically on a 6 to 20 scale. Now that might seem kind of weird for people like, oh, why is it not 1 to 10? 1 to 10's kind of typical what people use, like a how hard is this scale? But it's called the Borg RPE scale. And the 6 to 20 is essentially because the, initially the theory behind that scale was that you would just add a 0 to whatever your RPE was and that would correspond to your heart rate. So say average person has a maximum heart rate of around 200. If I give you an RPE of 18. That means my heart rate's probably around 180, which is a fairly high-intensity. Whereas maybe my RPE right now is a 6, maybe my heart rate's 60. That's like a resting heart rate.

So that's kind of the idea behind that scale. So people kind of can understand what, what, what that means and why we're doing 6 to 20 versus 1 to 10. Another way is to use the talk test, and that's essentially just like, are you able to do a full conversation, barely get out words, or not talk at all? That's kind of another way to, to kind of gauge zones. And the final way to describe the zone is to be based on your percentage of your maximal heart rate. And a lot of people have heart rate monitors, so they're going to be able to measure their heart rate during exercise. So we're gonna define zones using all 3 of those kind of metrics. So if we look at zone 1, this is going to be a recovery intensity. This is pretty much easy as you can go.

It's not resting, but it's very, very light activity. So on the RPE scale, this is going to be anywhere from a 6 to an 8. Um, it's going to be about 50 to 60% of your maximal heart rate. And if you were going to use the talk test to measure that intensity, it would be, you could hold a full conversation. So what you and I are doing right now, Rhonda, just talking, having a podcast, you could basically do that if you were in zone 1 or recovery intensity, cuz you're going on an easy walk or, um, something like that. Zone 2 intensity. People will hear about zone 2 training all the time. This is still a light-to-moderate intensity exercise. So it's gonna correspond to an RPE of about 9 to 12, 60 to 70% of your maximal heart rate.

And then the talk test, again, you should be able to have a conversation in zone 2. If someone were listening to you, they could probably tell you were exercising, but in general, you could hold pretty much a, a full conversation. And so these, you know, zone 1 and zone 2, those are gonna be your light to moderate intensity exercises. In particular, you know, that zone 2 training, good for kind of Building your aerobic base. Then there's zone 3. This is kind of veering into the territory of high-intensity interval training. It's thought of a lot as your threshold intensity or maybe steady-state exercise. It's gonna correspond to an RPE of 13 to 15, about 70 to 80% of your maximal heart rate. And then this is where talking gets a little bit difficult. So you could speak in broken sentences.

It's still not, you're not gasping for air yet, but you could speak in broken sentences and that would be a good way to indicate kind of this zone during, uh, using the talk test. And then zone 4, this is where you get into the high-intensity training. Um, so it's a 16 to 18 RPE. It's, um, you know, 80 to 95% of your maximal heart rate. And you could probably only speak one word or two at a time, maybe if you were trying to gauge that zone based on the talk test. And then zone 5, that's maximal exercise intensity. That's your VO2 max. It's as hard as you can go. So RPE 19 or 20, it's 95+ percent of your maximal heart rate. And then you shouldn't be able to talk. So if you're doing, uh, you know, Tabata intervals or something like that, this is zone 5.

You shouldn't be able to talk at all during that exercise intensity. So those are the 5 zones. And I think what's cool about having all these different metrics to define the zones is that, you know, if people don't really want to train using heart rate, or maybe they don't even have a heart rate monitor, they can use the talk test, they can use RPE, or maybe a combination of all 3 of these. And they're pretty reliable. I mean, they've, all of these have been kind of well evidenced to correspond to the different zones. But I think what's nice is that people can use these to train and it doesn't require a lot of technical ability, a lot of experience.

Dr. Rhonda Patrick: And so this is, I think, you know, in my mind, the best way that people can think about kind of training intensities is using the zones as we define them here, or at least using those as a guide. I, I really like the talk test way of defining it because I, as you were sitting here talking about this, I was thinking about my, my whole exercise protocol and I'm like, okay, oh yeah, that's actually what I thought was more zone 2 is really more zone 3, what I'm doing here. With respect to heart rate monitors, do you, I, I know Levine mentioned there can be a lot of error with using something like a smartwatch. And is there more accuracy in using something like a chest strap, like a, maybe a Polar strap versus a smartwatch versus like the talk test?

So let's say you don't have a chest strap, should you be using a talk test or can you still use your smartwatch? Is it still— what's more accurate?

Brady Holmer: Yeah, I think the accuracy of the smartwatches is, is obviously there. They've been, you know, validated against EKG and things like that. But as Levine mentioned, and as others have kind of drawn caution, they tend to get less accurate as the intensity of exercise increases. They're not perfect because, you know, it's getting your heart rate reading from a sensor on your wrist versus your chest. So I would encourage everybody to invest in a heart rate chest, you know, a chest strap monitor. It's less than $100 investment. It's going to give you A lot more accurate data.

Some people find them uncomfortable, but most of them now are, are pretty comfortable. And if you really wanna train using heart rate, I would say invest, invest in the chest strap. But you know, the, the watches aren't totally off and they can be used as a good kind of reference as to, as to where you are. But like I said, in my experience, and I think the experience of others, the harder that you go, the higher the intensity goes, kind of the less accurate that they get. So if you wanna use heart rate, great. It can be a good indicator. But the talk test is a very good, I think, way to assess your exercise intensity, especially for people who are newer.

So I think one of the, not flaws with RPE, but one of the caveats is that you need a little bit of experience to really know where you're at, like how hard something is. I mean, if somebody has never actually gone to a maximal intensity, then how do you know, how do you know what a 20 out of 20 is if you've never really reached the point of volitional exhaustion? So if somebody is just beginning to exercise, they might be at 70% of their Maximal intensity, but they might think that they're at a 20. So it takes time to learn kind of what your RPE is to be able to assess them accurately. So I would say, you know, if people are more experienced with exercise, then you could use something like RPE to kind of gauge your intensity.

But those newer to exercise might actually have a lot of good feedback with the talk test. I even kind of use that. I mean, you know, it's if you're running with a group of people and you can have a conversation, okay, well we're probably in zone 2. If I'm really struggling to like breathe, then I might be in zone 3, 4, or even 5. So, I think it's a great way to use the talk test. Anybody can use it, but I think newer people might benefit more from that. And I think also what people can think about doing is using a combination of all 3. You know, you can use heart rate, you can use RPE, you can use the talk test and maybe see if those, you know, correlate with one another during exercise. But use all of those to kind of inform your exercise intensity.

Dr. Rhonda Patrick: Exactly. Yeah.

I, I usually am not wearing, I do have a chest strap. I have a Polar chest strap. I have used it before, but I'm not typically wearing it when I'm doing a workout. And so I, I think using my, my smart, my Apple Watch along with the talk test, 'cause I often have someone with me when I'm working out, is like, okay, well maybe, maybe it's not entirely accurate as I'm getting into my zone 3, perhaps zone 4, but I know I can't talk more than a word. So it's clearly like, it's good to combine them both.