Transcription
It's time to talk about Zone 2, baby. That's right, Zone 2, the miracle training intensity. We're going to break it all down. Is it actually a miracle? Uh, no. Is it good? Probably.
But I'm going to break down all the science and then more so the training and application, so that you understand when all of the health fitness influencers from Peter Attia to everybody else in the world is talking about Zone 2, you know what is BS and what to take away from it. So let's start off by giving us the simple definition of Zone 2.
In endurance sports, we tend to categorize our training often with a five-zone model from 1 to 5, from really slow to pretty dang hard. Essentially, Zone 2 is in what we call like the easy to kind of steady pace intensity. Often, if we look at heart rate, it's about 60 to 70% of max heart rate.
If we look at the physiology of what's going on, it's when our fat burning is the highest. When we have the highest rate of fat burning, so we're not so intense that all of a sudden we're relying more and more on carbs and we're shutting down that fat burning because the fat can't provide the energy fast enough to sustain the intensity. We're at that high fat burning rate, and that's something that is often pointed out by Peter Attia and others as the key factor.
If we look at it from a lactate standpoint, okay, lactate, one of the end products essentially of glycolysis, our lactate levels are still relatively low. They're at what we'd call lactate turn one essentially, which is between 1.5 to 2 millimoles for most people. It varies a little bit, sometimes a little lower, but it's at a state where we're we're not rising, we're very steady in this kind of low lactate zone.
Okay, what happens if we go a little bit faster? Lactate levels go up a little bit higher. We're still not at lactate threshold where they start going up near not exponentially, but a fast rise. But also around this time period or around this intensity zone is when we get around Zone 2, we are primarily using slow-twitch fibers. So those slow-twitch fibers have a ton of mitochondria, which allow to fuel us aerobically, which allow us to utilize fat as a fuel more so.
As we go a little bit faster, we start dipping into our fast-twitch or intermediate fast-twitch, slow-twitch mix fibers because we need them to sustain the intensity as we get faster. Okay, so all of that being said, all of that occurs. We also occurs around here is one of the ventilatory thresholds. So our breathing, if we go a little bit faster, our breathing goes from relatively controlled to now we can only say short conversation or short sentence or phrases.
Well, all this sounds good in theory, and there's some sort of truth behind it. What the reality points is that Zone 2 is kind of undefinable. That's because the boundaries between these zones, as a recent review article found looking at experts and their opinions, found that it's more nebulous. It's more like a dimmer switch instead of an on-off switch.
And we can see this in the research that has looked at trying to classify Zone 2, whether by fat max, what we just talked about, by percent VO2 max, by blood lactate, ventilatory threshold, various blood lactates. It's all over the place. The percentage of, you know, power output, peak power output, or if we looked at it as percentage of race paces, all over the freaking place. And the point is this: these zones are not the laws they're made out to be. They're rough guesses, they are rules of thumb, they are categories often with very arbitrary markers that distinguish them. And that's point one, which we're going to get into.
But let's dive into more about why in the world we do Zone 2 and what the claims are on what it does. So why does everyone say this is the magic? Okay, there's various theories here, but they both basically center on two things. One is mitochondria. So if you look at Inigo San Millan's research, great researcher, has some good stuff. His theory is essentially that we need mitochondria development, not only for endurance performance, but that is that the heart of health. So before we see things like type 2 diabetes or other medical problems, we often see problems at the mitochondria level first. That's San Millan's theory.
So the idea is, if we do a lot of Zone 2 training, which is when we're recruiting most of those slow-twitch fibers, which have the biggest capacity for the mitochondria, we're going to be healthier because we've gotten the underlying thing that often causes metabolic issues later, more mitochondria, right? We can handle more load, we can take up in that glucose effectively and spare ourselves glucose and glycogen, and we're in a good spot.
The other kind of theory that combines around this is that fat burning zone, right? If we can increase that fat burning zone, our efficiency in that, our capacity to burn fat and delay utilizing carbohydrates, it helps not only with mitochondria but health, and depending on the race, as long as it's not super high intensity, even performance. That's the theory. Let's break it down.
Here's the problem. When we look at the mitochondria side, there are various ways to get mitochondria changes or what we call biogenesis, creation of more mitochondria, expansion of more mitochondria than just easy running. Zone 2 provides a good stimulus, but if you break down the science, and not going to go all the way deep, but what happens is we have various signaling pathways. Essentially, it goes like this: we activate a signaling pathway, that signaling pathway eventually tells us, hey, we need to adapt and change, which means we get some sort of gene transcription, which then creates some sort of functional change, as in increased mitochondria, which then leads to some sort of practical performance change, right?
So think of it like this: activate the signaling pathway, tells the body, hey, we need to create more of this stuff, get the building blocks to create more of this stuff or adapt in this way. We adapt, we get a functional change, build our powerhouse of mitochondria or the ability to transport or whatever it is that leads to performance improvement. Right?
But here's the problem. To get that gene transcription, to get that signal that says, hey, more mitochondria or alternatively, more efficient mitochondria, there are multiple different signals we can send signals in different ways. Again, not to get confused, but we have all these acronyms, CAMK, MAPKK, we've got PKA. All of these things which eventually hit PGC1 alpha. Alphabet soup, I know. But with every one of those different signaling pathways is a different thing that activates it. For instance, CAMK is activated by changes in the kind of like calcium level. MAP kinase is altered by reactive oxygen species in there, so things like you might have heard free radicals. AMPK is altered by the kind of like balance between AMP and ATP.
So the point is, we have all these different triggers that send us down a different signaling path, which all result to some degree of mitochondria change. And what we know is that different intensities and volumes and frequencies hit these different signaling pathways to varying degrees. For instance, again, it's complicated in reality, there's more than just these handful of signaling pathways. There's probably dozens, many of which we don't understand or haven't figured out yet. But help you understand, for example, high intensity is more MAP, MAPL, which is a variation, we won't get into it. Moderate intensity, more of like a MAP kinase or AMPK kind of hits it a little bit harder. Longer duration has a, hits different pathways in a different way, but tends to lead to a greater increase in that PGC1 alpha than shorter durations.
And the point is, all of these different intensities can activate a different pathway and get us to the same functional result, which is exactly what a recent meta-analysis that just came out the last couple months found. When they compared, they didn't look at all the pathways, but they looked at the different training types and looked at all the studies and said, hey, how does this impact mitochondria and then VO2 max and two degrees, some performance test. What they found is that in their categories, in endurance training, high intensity or sprint training, which it's not sprint training, but just think of it as like easy to moderate, moderate to hard, and then very hard. In those three categories, guess what? It was a similar extent of mitochondria development in every single one, basically plus or minus 25% improvement or a gain.
What they did find is that higher training frequencies, regardless of what it included, were associated with larger increases in mitochondria content. So the point is, everything works. Why? Think of it as a freeway system. Like sometimes it's like the road needs expanded, right? Sometimes to drop our stuff off, like our shipment off, we need more people to help unload it to get it into the warehouse. Sometimes we need a bigger warehouse to store and process it. It's the same in our body when it comes to mitochondria and development at a whole. And what happens is we need these varying intensities to address different levels of all of those different processes to get the energy into the cell, processed, and then out, right? It's the same here.
So let's step back. We've talked a lot, a lot about some of the science here, okay? And by the way, the same goes when we look at the science of fat burning. I'm not going to use it as well, but there's research that shows that, for instance, training at lactate threshold can help with your fat burning, maybe not directly, but it does. So because it expands the possibilities of easy paces. It goes from easy paces are from 9 minute to 8:30 to now 9 minute to 7 minutes because we've increased that gap between our easy pace and our lactate threshold, for example. Same goes with other things, okay? That gap has expanded. And this is why you see elite runners have more often a larger variety of easy to moderate paces than Joe Blow. Because Joe Blow, Joe the jogger, what happens, and there's data on this, like when they go from walking to even jogging at the slowest time period, there's very little zone or intensity there where that lactate doesn't just go up, up, up, up, up and up. All right.
So what's the point here? Is Zone 2, should you train at it? Absolutely. Here's why. Not because of such and such science or what have you, although it helps to know it, but because we have a long history of training that tells us that we need to accumulate a lot of relatively easy to moderate training. Okay? If you look at the history of training, we tried basically everything. No easy running, all easy running, easy running was really slow, everything where it was really steady, every mix in between. And what's happened is training history has progressed where we said, hey, we need a variety of everything. But what builds the foundation is a lot of easy to moderate training. And that allows us to get better at the interval stuff, the speed stuff, the high intensity stuff. It allows us to work. This is where Seiler's famous 80/20 observation came from. He looked at the training of elite athletes in a variety of sports and said, hey, they're all doing a lot of easy work.
But here's the key. If we look at the zones, and when people say Zone 2, it's an arbitrary distinction. I mentioned, you know, it's that around lactate turn one, or it's when fat is max. What we know is our zones aren't light switches. We don't turn it on and off. They're more like a dimmer switch where we don't know distinctly where these zones end or begin because there is no beginning or end. Even if we looked at lactate threshold, very rarely a beginning and end, it's more of a blend depending on the day, intensity, everything else around it. Okay? So what happens is we use these zones for categorizing training, but if we fall into seeing them as laws, we are in trouble. That's not how it works.
So if all the zones blend together, why in the world do we do Zone 2? How do we do it? And does it really matter that much? As I said, history tells us it does, to a large degree. Not that it's the only thing, but it sets the foundation for everything else. Why? Because if we don't have a decent fitness, which often comes from easy running, because that increases all those central adaptations in terms of cardiovascular and peripheral in terms of mitochondria capitalization, really targeting the slow-twitch fibers, when we have that fitness, then we get fit enough to train. And the fitter we are to train, the more expansive those quote-unquote zones are, and the more intensities we have to play around with.
If we don't have that, then literally, we go from our intensity, almost shrink, and literally go from, hey, we can walk to like, even jogging makes our lactate go through the roof, our heart rate spike, all the fatigue byproducts go through the roof, and we don't have a very broad intensities. So it gives us more optionality. So that's why, again, Zone 2, quote-unquote, lays the foundation. So it's not bad, it's just we have to understand what it is. And it's also not specific. Whether you train in the high end of Zone 1 or low end of Zone 2, or middle, or high end of Zone 2, or even in the low end of Zone 3, like there's no distinct barriers that say this is the adaptation you're going to get. You need all of them to varying degrees.
And this is why, if you look at runners, what happens is we often settle into a middle-ish ground where most of our runs are high end of Zone 1, low end of Zone 2, mid, moderate end of Zone 2 for most of our normal distance runs. Where if I say, hey, today go run 9 miles, it generally falls into that. But there's variation. If I say that, generally puts us at maybe 6:30 to 7-minute miles for me right now, right? There's variation. Some days I run 7:30 or 7:45 pace, why? Because my body needs a little bit more recovery. Some days I feel good and I might start off at 7-minute pace, but I drop down to 6-minute pace or even high fives or mid-fives sometimes, why? It's feeling good, you press that aerobic adaptation. That is not bad.
Which brings me to the point. Sometimes in these fitness influencers, for instance, Peter Attia, who has some brilliant work and some, his book was solid, but he gets this false idea of precision of saying, hey, I need to measure lactate and get precisely in the spot. First off, our lactate analyzers are not that accurate. There's data on this, there's research on this. They're not that accurate to give us that sort of precision. Okay? B, we can't tell if that precision actually matters for getting the adaptations. In fact, it probably gets in the way. As I said, we need to run in the gamut of Zone 1, 2, and even low end of Zone 3 for our easy to steady running. Okay? So we don't need that false precision. Don't measure lactate.
And this is coming from someone who, when he was, I think, 19 years old, asked his parents for a lactate monitor so I could go prick myself, take my blood, figure out my lactate down at the track. And they got me one for Christmas, and it was great. So I still have one, I mess around with it all the time. But it's, it gives us this false precision in this idea. Same with heart rate, okay? I get it, it can help depending on the situation. But if you think that, oh my gosh, if I go five beats over, I'm in the next zone and my workout is ruined, it's, it doesn't work like that. Zones are dimmer switches, not light switches, not on-off switches. You're not going to ruin it. Sometimes it'll actually be good.
Okay, the other part of it, okay, let's step back. If I say lactate or heart rate, what do you do? You go by feel. And yes, you got to understand and train that, but it's, it's pretty simple. The goal is to accumulate a decent amount of volume. That's what easy to moderate running does. Decent amount of volume, long enough to allow the stimulus to absorb from multiple directions of easy to moderate so that we build that mitochondria, cardiovascular system, the roads to the powerhouse, the capillaries that help transport things, the whole system. You need to do it for a long period of time. It's why Frank Shorter said, two hard workouts, long run, as much mileage as you can handle for years, then come back to me. It's why Lydiard said, hey, we need a long block of easy running plus strides essentially to build this foundation. Okay? That's what easy to moderate running does. It's why Seiler said 80/20 rule. It's all saying the same thing in different words. Okay?
So what we have to do is spend a lot of time going easy where we can have full-on conversations. Now, sometimes those conversations should be like me talking right now, where there's basically no sign of out of breath at all, zero. Like you're having a conversation with your friend. Often those are recovery or easy runs. Sometimes the conversation should be like you're having a normal conversation, but you got to have a little break every once in a while where it has to be back and forth so you can breathe. Sometimes you're going to want to be able to have a conversation where it's a little bit challenging, but you can say a couple sentences, a couple phrases, and then you got to stop and breathe. Well, not stop, but you know, not talk and breathe. And those are the gamuts between recovery and what I'd call steady. And then once we get above steady, we start going into lactate threshold and then above.
Okay, so for Zone 2, when you hear that, think mostly full conversations or almost full conversations, and a little bit part conversations. On all of these, you should finish your runs feeling like, hey, I feel good and I could do more. And that's it. You do that, and you can consistently do that, you're in a good spot.
Now, for the rest of it, when we venture out of Zone 2, I said, hey, we need other or Zone 1, 2, 3-ish, we need other stimulus to get this mitochondria adaptation. Absolutely true. And this is why in other videos I've covered when we talk about tempo runs or thresholds or intervals or high intensity or sprint intervals or VO2 max or whatever, doesn't matter. Here's the thing. Remember back to that signaling pathways, even for just creating mitochondria, we need to run the gamut from threshold or tempo run steady all the way down into what we call sprinting max or more so for mitochondria speed endurance or mile 800 pace work. And you need the gamut of it. I've gone into it detail previously. I'll go into more detail on that moderate to high intensity, more so. But the rule of thumb is, vary it up. Vary it up. Do what you can handle. Almost always have one more rep in the tank. And if you do, that's why we call periodization. Do it when it matters. Varied up. But if you do that and sequence it right, you're going to get the adaptations.
So the bottom line, Zone 2, it's great. We need lots of easy running. It's not a law. It shouldn't just be Zone 2. We should also have Zone 1, should also have Zone 3. We need a mixture of basically easy to moderate, a lot of it, accumulated for a long time. Don't drive yourself nuts. Don't be religious about it saying, I must be in this heart rate or this lactate. It's false precision. It's not reality. Can you go too easy? Sure. If all you do is run 10-minute pace when you're a low 4-minute miler, at some point it's not going to be a stimulus for adaptation and it's just recovery. But most people don't do that. Most people settle into, hey, this is relatively easy enough and I'm going to be okay. And that is true.
So there you go. The download on Zone 2. Hope you enjoyed it. Hope it helps you kind of sort through the mess. If it does, support my work, check out my books, subscribe, leave some comments. This is what we do. Take care, everybody.