A (3:50)

So there's a bias almost built into the system. So it's more fun to do research on high intensity. It's more likely to get published. Therefore, the media are more likely to pick up and disseminate this information. And so we are seeing a small fraction of the work. But thinking that this is, that's the whole thing.

B (4:12)

Right. So we're seeing the, the part of the, the big iceberg that's visible. It's got to be sustainable. And if we do too much hard high intensity, the recovery times get longer, the risk of injury gets higher, and on average it doesn't pay off. So, yeah, there are some sessions that are hard and they're feel rewarding to achieve, but they are achievable because of the sustainable process.

A (4:40)

Well, let's talk about this 8020 rule. 80% low intensity. Right. Because if you're not familiar with this research, if you haven't been following your work or Inigo Samlan's work, or, you know, other researchers in this field, you may assume that if you want to be really fast at running, let's say that you need to practice being fast at running.

B (5:06)

Running really fast. Yeah.

A (5:07)

So every time you go out, you need to be running fast because that's how you get faster. But I think what your research is showing is that that's absolutely not necessarily the case. And I also very much appreciate that you say that you didn't create this.

B (5:21)

No, no.

A (5:22)

Right. You coined the term maybe, but you didn't create this. You simply observed what the very best were doing.

B (5:29)

That's right. When you have a very clear outcome that you have to achieve, run faster for 10,000 meters, that gives you a quite clear outcome. And you say, all right, if I train more high intensity, does that help? If I train longer duration, does that tend to help? So this, the 8020 has evolved in the crucible of having very clear performance outcomes. That you have to achieve. So they have these clear outcomes and it's a kind of a Darwinian process. They can try more intervals, they can try more volume, they can try training three times a day. And then they're slowly their coaches and you know, through experience they're going to settle in on a methodology. And what we saw was, is that interesting, the rowers and the runners and the cyclists who really don't talk to each other, they've all landed on basically the same distribution. And in my mind that suggested, okay, there must be some universality here, some universal truth, a self organizing process. And that's what got me really excited about it.

A (6:39)

Now. I think your message of 80 20, at its core, it should be really empowering for people because I can think of so many patients right now who over the years have been put off by movement because they think it has to be sweaty, it has to hurt, it has to be painful. And actually this 8020 approach is saying, guys, you got it wrong, you don't need to. 80% of it actually will be quite enjoyable. You won't be sweating, you'll be able to have a conversation. Do you know what I mean? I think that's a very important message.

B (7:15)

80%, I got excited, sorry. When you do the 80%, the 20% also feels better. It's challenging, but you're able to do it and you're, you know, so it's a, it's a virtuous relationship.

A (7:30)

Why does the 20% then feel easier or enjoyable?

B (7:34)

Well, you know, it's not easier, but in the sense that you are working hard, but you have now built machinery that allows you to actually mobilize your capacity more completely. You're actually able to use your heart up to close to heart rate max because you have the capacity in your legs that can be supported. So it's an interesting, you know, the building up that basic endurance. That's why we see that it also improves maximum capacity in elite athletes. They have to have the volume, just, they have to train quite a bit of low intensity to really pull out the maximum capacity.

A (8:14)

Also, one thing I've realized, let's say I'm on my indoor bike for an hour at a low heart rate, it feels easy, right? Pretty easy. Like I'm like, yeah, I could keep going, it could go longer, could go longer, right? And when I finished, I often feel I haven't done that much. Right. Not only that, Steven, my recovery is super quick. And I find that when you do low intensity work, you could do more. You sometimes don't feel you've actually done that much compared to the high intensity stuff.

B (8:52)

You might even forget you did the workout. Yeah.

A (8:55)

So let's go back to this 80% then at low intensity. What does low intensity mean?

B (9:02)

Yeah, in layman's terms, if someone says, well, where do I need to be in this so called low intensity? Which I often, I use colors, you know, green, yellow, red is what I've tended to say. All right, so green zone training. If they take off running and after it takes a few minutes to kind of come up to speed, your body warms up, literally. But from about 15 minutes into that run, that's going to last, say an hour, the heart rate should stabilize. It shouldn't just keep drifting up, up, up, it should flatten out. And they should come into a routine where they're just like, they're able to think about other stuff. They're able to be distracted by the flowers and the trees and the bees around them. They're not having to concentrate to maintain that intensity. They should also find that they can talk. You can share sentences with somebody running beside you and say, did you see the game last night? And so forth. So that's another working person's kind of measure. And when they're finished with that one hour of running, they kind of just, let's go eat. Is dinner ready?

A (10:13)

So they're still hungry, they're ready to.

B (10:15)

Go straight to the dinner table usually. And you say, well, what in the heck does that have to do with anything? Well, it's an indirect indicator of whether or not they've turned on what we call that sympathetic stress response. Because in that classic fight or flight stress response, what happens when we have to run from the tiger? Our body says send blood to the muscles, take it away from the stomach. Right. We've got to shift our reserve so appetite and things like that are reduced. For a period. After a high stress workout, you can't even look at food for the first hour. After a really tough interval session. Right. You can go straight to the dinner table because you haven't turned on that big stress response. That's a nice indicator, but it's one so flat heart rate can talk together and go straight to the dinner table.

A (11:10)

After you mentioned flat heart rates, not everyone, of course, measures their heart rate when they're training. So in terms of something that's really practical for people, you're saying a lot of this low intensity work is being done so that whilst you're doing it, if you were with someone else, you could have A conversation with them. Yeah, yeah. So I think some people call that the talk test. Maybe the talk test.

B (11:37)

Now, the talk test is not perfect, but it's often no one tool, no one measure is perfect. But when we put it together, there are some people that will manage to be able to talk when they're working too hard because they're just good at it, you know, and others don't want to talk at all. So. But that is a nice test that we can add. And so you don't have to measure heart rate, but it can be nice to do sometimes. That green zone is what we call steady state. Things are pretty flat. But when you're in that yellow zone, it's slowly feeling harder and harder. The body's having to mobilize more and more because you're running out of glycogen, muscle fibers are getting fatigued and so forth. So it's, it's a non sustainable intensity in the long run. But it, it's a very, we need to do some of it. I'm not saying we don't, but number one, it, it will turn on some stress responses. It'll take longer to recover from. And particularly when we also go into that third zone, that really high intensity where now heart rate is above 90% often we're, you know, really breathing, we're counting minutes. Minutes, yeah, we're down. I mean, this is the other interesting thing is when you're in that green zone, you can kind of forget the time you, you say, oh wow, I've already done 40 years. Right. Because it feels quite sustainable. Then you get into that yellow zone. The brain, the mind kind of starts to zero in. You start to scan your body as you're working. You have to be more purposeful, you have to be more focused. We're in your, in the green zone. You can be talking with your, your pals, you can be thinking about other things and so forth. The, the, the brain can kind of go on autopilot, but there's this inward focusing that starts to happen in that threshold, that yellow zone, and becomes particularly, you know, you really have to focus in the red zone. That's the typical pace where we will break things up into pieces. We'll break the pie up into what we call intervals. That's when this interval training comes in. And so then the coach or the fitness center will say, okay, today we're going to do six times three minutes. So that they're saying that you're going to do little bouts of work for three minutes. They're Going to be quite hard, but then you're going to get a short recovery period. You won't fully recover, but you'll recover some. And so it will allow you six times three minutes, what's that add up to? 18. But if I told you today you're going to do 18 minutes at that exact same pace, you wouldn't be able to do it.

A (14:09)

So you have to rest.

B (14:10)

Yeah. So you're now at an intensity that by breaking it up into smaller pieces you can accumulate more time.

A (14:19)

Now I think it's important to understand that staying in the green zone for 80% of your work will also help you get faster and perform better. Right?

B (14:29)

Yeah.

A (14:30)

One of the kind of core messages coming out of your work is that we need to spend most of our time in this green zone. And if we do that, we'll get all kinds of performance benefits, metabolic health benefits, you know, just health and well being benefits, frankly, full stop. Because it's a low stress zone as well. So we're not generating cortisol and adrenaline. And I think that also speaks to the stress load of training. Like if you're training at a low heart rate in that green zone, actually, you know, it's having less of a stressor effect on you in many ways. Does that make sense to you?

B (15:11)

It's exactly what we're, what we're basically trying to manage. Where I say that for me, training intensity distribution, after doing research on it for over 20 years is all about managing the relationship between signal, adaptive signal that I'm trying to create, signals for more mitochondria and capillaries and stress, which is a systemic phenomenon. So the local adaptations, they're happening in the cells, the muscles and the capillaries, but the stress response is more of a systemic wide response. So I'm trying to manage now I can't, I don't want to get rid of all of this, but I want to get that ratio in my favor. And green zone training gives us a high adaptive response at very low stress. We're trying to stay under the stress radar. Most of our workouts.

A (16:06)

Yeah.

B (16:06)

But then some of our workouts, then we say, yeah, today's high stress, it's good, but I built it in and I have a plan because tomorrow I'll go easy and the day after that I'll still go easy because I'm building in some recovery.

A (16:17)

Yeah.

B (16:17)

Okay. I'll tell you this last story. Maybe what got me started doing research on this intensity distribution. One of the key moments in my scientific life was I'M out jogging in one of the local forest trails in Norway, and I see a young woman, she's jogging in front of me, and then she comes to a fairly steep hill and she starts walking up that hill and then she gets to the top and starts running again. And the reason that was jarring for me was because I knew, I had tested her. I knew she had a VO2 max that was quite high, meaning she was a very good endurance athlete. Her sister was an Olympic silver medalist. And I was like, why are you not running up that hill? Even I can run up that hill. But then I learned. Well, no, because that day was a green zone day for her. And she was exhibiting intensity, discipline. And that was this moment of truth for me is I realized, okay, I got to rethink this. What I thought I understood about training, because there's knowledge here that I need to understand.

A (17:33)

I love that. It's a beautiful story. Very, very inspiring. There's almost a conflict, which is we know that physical inactivity is one of the leading causes of death globally. We know that a lot of the population are not meeting basic government guidelines for physical activity. Right. And we're now saying, yeah, be active, but be careful when you're active. Can you just help people understand that?

B (18:02)

Our great great grandparents, you know, they would have had jobs that were quite physically demanding as a rule. They worked on farms, they worked physically. And so they were getting a lot of green zone training, but they never called it training. Yeah, it was just life work. It was like putting food on the table. Right. But we've almost eradicated jobs that require us to use our bodies in a physical way. The famous study from the double decker buses, this was some of the start of epidemiology research and physical activity. The bus driver wasn't getting physical activity. The conductor, the person who was taking tickets or whatever, up and down. The two double decker bus was more protected from heart disease.

A (18:51)

Wow.

B (18:51)

Right. So we've seen this in these basic things in normal work have disappeared. We push buttons. Even the farmers, even the traditional factory workers, you know, they're no longer doing heavy labor. They're not getting the big heart rate, you know, they're not lifting anything. So it's all gone. And that means we have to somehow synthetically, artificially bring it back into our lives because our genetics needs it. We're still built for movement.

A (19:23)

Yeah.

B (19:24)

If you're getting out the door three or four days a week, then good things are going to happen. So, yes, we've been on the sofa a lot. We're out of shape, but lucky for us, our genes are there still waiting for us to offer the right stimuli. And there is so much, what should we say, unexploited capacity that we can tap into if we just make it.

A (19:50)

Sustainable for that individual who fancies themselves as a bit of a weekend warrior. They work hard in the week, they've got kids, but they like to push themselves. They like to do the park run, they like to do 10Ks every few Sundays when there's a local event on. I know many people like this, but they're feeling tired, they're not getting faster. They wish they could run faster or be injured less. What would your words of advice be for that individual?

B (20:24)

I would say to them, just put a little bit of trust in me for six weeks and follow this guidance that we're going to reduce the number of hard sessions. If you're doing two or three times a week, probably three times a week, they're going pretty hard. I'm going to say, can you let me have two of those? You keep one really hard, give me two. And I want them to go into this green and we'll stretch them a little bit. Give me six weeks of your time as an experiment and let's see where you're at in six weeks.

A (21:02)

And what do you want them to assess? Is it sleep, energy, performance, all of these things, I'm guessing.

B (21:08)

And they may, it happens surprisingly often. They may say to me in an email, you know what, I haven't run this fast in 10 years. And I'm being totally honest with you, I get so many emails that say because it surprises them so much, I'm running slower in training and I'm faster in the 10k. I don't get this, but it's true. So just give it a six week try.

A (21:37)

Okay, great advice for them. And then they could also forget about a seven day cycle and go, okay, I train three times a week, but one in every five sessions is going to be intensity. So therefore you, you know, because we have this seven day model in our head, but we don't have to train to a seven day model, do we?

B (21:56)

That's right. And I've talked a lot about this. Even my own daughter who I coached as a runner, that's what we did is we changed the seven day cycle to a 10 day cycle. Her personal records, you know, ran a 1:16 half marathon. You know, it got better. She said, she said, papa, now I feel flow in my training. I still remember that she used that term now the training is flowing.

A (22:22)

Hope you enjoyed that bite sized clip. Hope you have a wonderful weekend. And I'll be back next week with my long form conversational Wednesday and the latest episode of Bite Science next Friday.