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#571: Is Zone 2 Training Actually Best for Health? – Prof. Brendon Gurd
00:38:27
In recent years “Zone 2 training” has gained immense popularity in fitness and health circles, often being proclaimed the “best” cardiovascular training for metabolic health. Zone 2 training is sustained, low-intensity exercise below the...
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- [00:00]
A
Hello and welcome to Sigma Nutrition Radio. This is episode 571 of the podcast. My name is Danny Lennon and you are very welcome to the show. Today we're going to be digging into the topic of Zone 2 training and particular looking at some of the claims that have become popularized about this type of training, with a particular focus on health outcomes and how this pertains to the general population who are looking to improve their cardiorespiratory fitness and their general health over the long term. And so one of the things that became popular in recent years is the use of Zone 2 training to do that. That comes along with a variety of claims about why it may be the best way to train for some of these adaptations that we'll get into. And one thing that caught my attention recently was a recent review article that was published in Sports Medicine and today's guest, Professor Brendan Gerd, was one of the co authors of that paper titled Much ado about Zone 2. And Kirsty Storeshuk was the lead author on that. And this review looked at some of these claims around Zone 2 training for the general population with the goal of improving things like mitochondrial capacity, cardiorespiratory fitness, and therefore some of the health benefits from that. And trying to walk through for the various claims that we have about it. What does the evidence say? What quality of evidence do we have, what quantity of evidence? And are we in some cases, are some people misunderstanding what the evidence actually says, or maybe just have heard certain messages that might be misleading and that could take them, lead them to take decisions about what type of exercise to be doing that may be counterproductive or may not be giving them the the type of optimization that they think it is giving them. And so I thoroughly encourage everyone to go and read the paper in full. I will link to that in the description box where you're currently listening. You can go and read that paper. And in addition to that, Professor Gerd has kindly given a set of slides from a lecture he gave around this topic that will be available again in the description box. You can go down, click open those and you can download them and go through them. They'll include a number of references for various things that we discuss throughout this podcast, as well as a number of images that are really useful to conceptualize some of these ideas. So go and check those out. You can go through that slide deck of those different images and studies and references that will supplement your listening here today. And of course, if you are a Sigma Nutrition Premium subscriber, you will get a set of detailed study notes going through everything that's discussed in this particular episode, breaking it down, giving definitions, using graphs, etc. To make sure you understand this content and get more out of it. So they will be in the description box. If you are a premium subscriber, if you're listening on the public feed and you want to get access to resources like our detailed study notes or episode transcripts or our premium exclusive episodes, then maybe consider supporting the podcast as a premium subscriber. Information about that will be linked up in the description box or over on Sigma Nutrition.com and so as a brief bit of intro, Professor Gerd is Professor in the School of Kinesiology and Health Studies at Queen's University in Kingston, Canada, and his research focuses on exercise physiology broadly and some of the adaptations at the level of skeletal muscle. In particular, his work explores how different intensities and types of exercise influence mitochondrial content and function in muscle tissue, with the goal of understanding how to therefore optimize health and performance through different types of training. And so, based on that and his experience and his specific area of work, I think he's uniquely placed to be able to answer some of these questions that we are going to get into. So with that piece of context, let's get to this discussion with Professor Brendan Gerd. Welcome to the podcast to Dr. Brendan Gerd. Thank you so much for taking the time to come and join me today.
- [04:28]
B
Yeah, thanks for inviting me to chat.
- [04:30]
A
Yeah, I think as I have mentioned to you in our correspondence, a recent publication of which you were one of the authors, really grabbed my attention. I think it did a fantastic job of breaking down a topic that has got a lot of interest and some of that is warranted, as I'm sure we'll discuss. But sometimes maybe that might be overplayed in certain contexts and can be a bit confusing for people. So hopefully we're going to get working through the contents of that, but also the wider literature. Before we do that, I'd love if you could give people a brief introduction to your academic background, your research interests and anything else through your academic career that may be relevant to our discussion today.
- [05:09]
B
So I'm a professor at Queen's University in Canada. We're in Kingston, which is about an hour and a half or, sorry, three hours east of Toronto. My research career is focused on like exercise physiology broadly and then specifically as an independent researcher. We've studied the mechanisms that determine mitochondrial content in skeletal muscle with a focus on exercise and different intensities of exercise and how different doses and intensities might influence mitochondrial content differently.
- [05:39]
A
And so that sets the stage, I think, perfectly, for you being the ideal person to discuss some of this literature, particularly as we're going to talk about some of the exercise adaptations that happen at the level of the muscle, particularly. People have heard a lot about these mitochondrial adaptations. But before getting to that, we're maybe it'd be worth taking a step back. And for people who maybe have vaguely heard this terminology before or maybe are new to it, or others may be quite familiar when we're talking about this concept of zone two training, can you give a useful overview of first of all, what this terminology means, maybe how it's typically communicated, and what you feel in turn is actually the most accurate definition for, for this Zone two training.
- [06:25]
B
So I will start with physiologically. We actually have three intensity domains. So moderate intensity domain, heavy intensity and severe. The moderate intensity domain is below our first lactate threshold. And when we're exercising in the moderate intensity domain, we have very low glycogen utilization. We tend to rely heavily on fat metabolism, and we have low accumulation of lactate and other metabolic byproducts. When we transition the heavy intensity domain, that's above lactate threshold and below critical power, maximal lactate steady state. We can sustain heavy intensity exercise for a long time depending on how high in the heavy intensity domain we are. But we start to develop fatigue, we utilize more muscle glycogen and we'll eventually run into muscle glycogen. So that heavy intensity domain is harder and it has more of a metabolic cost. And then when you go above your critical power into the severe intensity domain, you're gonna fatigue really quickly. It's very difficult. You will reach VO2 max. Breathing is very heavy, and you're gonna last minutes before you have to stop. So the zone 2 typically is in a 5 zone model of intensities. And usually zone 2 falls at the top half of moderate, the moderate intensity domain. So it's below lactate threshold in that pretty easy intensity domain where we're again relying on fat, not utilizing a lot of carbohydrates, not accumulating lactate or other metabolic byproducts or fatigue.
- [07:58]
A
So with this Zone two, why is it that it has become such a focus? In other words, what do we know happens at this type of activity that first got people interested in maybe doing a certain amount of training here or having a focus? What is it specifically about this particular range?
- [08:16]
B
Yeah, so I think the answer to that question is that elite endurance athletes do a lot of Zone 2 training. So I'm sure we'll get into this. I don't think there's much special about that intensity that's going to induce adaptation, but athletes do do a lot of it. So traditionally there's a type of training called polarized training, which is 20% high intensity, typically in that severe intensity domain, and then 80% in moderate or zone two. And that's, you know, that's in elite endurance athletes. They're doing massive volumes of training compared to what the general population would do. And they do do these really high volumes of low intensity as part of that polarized training intensity of distribution. So I think that's where the, like the buzz on the Internet comes from, is that this is what the best athletes in the world are doing. They have the highest VO2 acts, really good metabolic health. So we should be copying what they're doing because obviously it's working.
- [09:12]
A
And so one thing you have mentioned is this lactate threshold that can give us this idea of when we are staying within certain limits. We can use this to determine which zones someone may be in that particular time based on this kind of five zone model. Obviously with that, that's reliant on someone having lactate testing or other forms that can be used in advanced labs. What are some of the ways that this equates to other, maybe more subjective metrics that maybe not technically are accurate, but that people may have heard about or will hear about when they're hearing recommendations about zone 2 in training?
- [09:47]
B
Yeah, so I think it's actually really hard to know where your moderate intensity domain ends. So where the top of your zone two training would be. Without doing lab testing and measuring lactate, Zone two can look really different in different populations. Elite athletes, I think Teddy Potagar was on a, on a podcast, said his zone 2 training intensity can be 320 watts. In some rides we have recreationally active young adults whose zone 2 lactate threshold would be like 60 watts. So that's a huge difference. So any sort of targeting a heart rate as a percent of max heart rate is probably not very accurate. Ventilatory response. Maybe you can kind of use that idea of if you're talking comfortably, you might be in zone two, but if you're a fit person with a really high lactate threshold, your ventilation is going to be high even though you're still in zone two. So yeah, unfortunately, I think if you really want to know, am I in the moderate intensity domain? You have to be either doing a lot of lab Testing or measuring your lactate, making sure lactate stays below 2 millimolar.
- [10:57]
A
Obviously, our focus today is going to be about general health because because of much of this interest right now, there's of course, a subsection of the population that may be doing it for endurance sport performance. And like you say, there are models of elite athletes that they may be basing that off, and there may be indeed more specific applications there. But I think some of the claims that relate to this being a benefit for health rely on a few different things that are all interrelated. Maybe one is on, like you said, V2 max. If we have a better V2 max that's good for metabolic health long term, then there could be even more specific claims around. Well, what we really want to do is get these adaptations at the mitochondria, and therefore zone two is best for that. Two parts, this question, and again, if this is too broad, we can narrow it down. But first of all, on that mechanistic basis, specifically related to the mitochondria, do we indeed see something unique happening at this intensity range that could confer a benefit to mitochondria in the muscle? Or where does that idea come from? And then maybe the second part, I'll wait to see afterwards.
- [12:01]
B
Yeah. So we've just published a review paper. It was led by my PhD student, Christy Starchak, and that was the question we were asking. We'd heard these claims that Zone 2 was the best for inducing mitochondrial adaptation. And as a. An exercise physiologist, somebody who's studied mitochondrial adaptation for my career, those claims didn't make a lot of sense to me. So the point of our review was to go into the literature, see what we could find about Zone 2 training and mitochondrial adaptation. And I think our main findings there were that it is possible to induce mitochondrial adaptations with zone two training, but it doesn't always happen. And zone two training is almost certainly not the optimal intensity for inducing mitochondrial adaptation. So if you want, if you're trying to maximize your mitochondrial adaptation, you want to target higher intensities of exercise.
- [12:56]
A
So, so when we're talking about these higher intensities, does that correlate to this five zone model as well, or is it more broad than. I'd be narrowing in on a specific.
- [13:04]
B
Yeah, I think you could use the five zone model. So I think my perspective would be, and this is sort of the way we think about mitochondrial adaptation in our field, is when you induce metabolic stress, you also induce mitochondrial adaptation. So as we go from zone two, where there's very little mitochondrial, sorry, metabolic stress. Into zone three we start to get metabolic stress and mitochondrial adaptation. And then as you go into zone four that metabolic stress and mitochondrial adaptation would be greater. And then again up into zone 5 again more metabolic stress, more mitochondrial adaptations. As far as like types of training, we would think that high intensity interval training at around VO2 max is probably the best intensity for inducing mitochondrial adaptation.
- [13:52]
A
Yeah, sorry to interrupt. So based on that, from the claims you may have seen outside of the literature that are talking about getting these positive adaptations, maybe for the moment we'll keep it to mitochondrial adaptations. But other things that relate to metabolic health and these health outcomes, are there any that you think take up their best point, make some decent points here that you are largely in agreement with. And at what point does it start to get into the territory where you think the evidence doesn't actually match?
- [14:24]
B
Yeah, I guess I would repeat, I think any claims that Zone 2 is the best intensity for inducing mitochondrial adaptation. That's probably not accurate. I think it's possible you can induce mitochondrial adaptation with zone two training. That's more likely the less fit you are. I think if you're a, if you, the fitter you get, you probably need to start using higher intensities of exercise to induce adaptation. Yeah, but I think that idea that this is a zone you have to do if you want to induce adaptation. My your mitochondria, that's, that's an inaccurate claim I think. Sorry, I just, I think this is really important that I think zone 2tr. Any exercise is good, any physical activity. So there's really strong data linking physical activity to reduced mortality risk. And the biggest decrease in mortality risk happens when you start doing something. So the difference between nothing and something is much larger than something and even more if that makes sense. So I think if you want to be healthy, be active, go for walks, that's going to make you healthier, it's going to reduce your risk of disease. But if we're talking about maximizing or optimizing optimization, that's where I think like zone two is probably the worst intensity. If you're trying to get like fast or fitter or have the most mitochondria you can possibly have.
- [15:43]
A
I'm glad you make that point about doing something is going to be beneficial because I think this is one of the things that sometimes because of the Claims of Zone 2 can get lost or can get to get damaged. That idea of just doing something right, it over complicates the situation sometimes for people. And one of the claims, at least I've heard is someone might say, well yes, you could do this high intensity training and again, at these positive adaptations with some amount of the work you do. And then the rest of the time you want to be down in like zone two. But then there's this follow on claim from that that if someone is unintentionally getting into zone three or zone four, they're in this kind of no man's land, so to speak. And I think the message people hear then is they're almost wasting their, their time from the outcomes that we're talking about with health. Where does this idea stem from that there's this kind of no man's land in the middle? This zone three is a bad thing if you move from zone two to zone three. And what can we glean from the research about this type of question?
- [16:43]
B
So I, I don't. From a physiological perspective, I think the data is pretty clear that if you go from zone two to zone three, you're gonna, you're gonna have more adaptations. And if you go from zone three to zone four, again, adaptations are gonna get better. So physiologically I don't know that it makes sense to like, you know, you cannot go above zone three if you're trying to induce mitochondrial or, sorry, above zone 2 if you're trying to induce mitochondrial adaptation, I think it's the opposite. You want to go above zone two. So I would guess where that idea comes from is again coming back to those elite endurance athletes. They're doing massive volumes of training, they're doing really high volumes of high intensity training and they need to have recovery days. They need to have days where they're not stressing their system, not accumulating metabolic stress. And so in those athletes, they want to stay below zone or in zone two, below zone three, so they're not depleting glycogen, not accumulating fatigue, so they can recover. And I think if your aim is recovery, if you slip up into that zone three and you start depleting glycogen, accumulating fatigue, now you're not recovering anymore. So in, in that setting it makes sense to me that you need to stay in zone two because you're trying to avoid stress. But for most of us who are doing physical activity, guideline levels of, of exercise, we probably don't need to worry about that. And, and I think we should actually be thinking about it the opposite way as we want to get above zone 2 as much as we can.
- [18:11]
A
One thing you've already alluded to. I'd like to ask to, to go back to that. This idea of first of all there's this preservation of glycogen we can have in zone two that we're not working at this high enough intensity. And one of the things related to that is that we're going to have this greater degree of fat oxidation. And then therefore because of this greater degree of fat oxidation, we're getting these positive adaptations at the level of the muscle. And again we again made to make clear there may be distinctions between sports and general health here, but there is these claims health wise that if we can have this training effect with greater degrees of fat oxidation, there's a benefit and that Zone 2 is uniquely able to do this. And once we cross into zone three, starting to lose this benefit. I know in your review paper you looked at some of the data to look at this question. Can you give an idea of what you found from the current state of the evidence?
- [19:03]
B
Yeah, so I think that the evidence is probably in, I guess in favor of zone two is probably strongest for promoting the ability to utilize fat. And I think there that maybe the effects of intensity are less clear from a. So I study the molecular adaptations to exercise and sort of the mechanisms that trigger adaptation. And there's an idea or a theory out there that by metabolizing more fat you're actually triggering mechanisms that induce adaptation. And so that would fit with this idea that we want to exercise at the highest fat oxidation possible because that's going to drive adaptation. So that idea is out there in literature. It's. There's not a lot of support. There aren't studies that sort of prove it to be that is true that if you want to induce fat ops fat oxidation you have to burn more fat. And in fact there's lots of evidence that and we know the kind of molecular signaling pathways by which high intensity exercise improves the mechanisms that determine fat oxidation. So yeah, so I'd say, sorry, that's kind of a rambling answer. But I think if you do zone two training, you can improve fat oxidation. But you don't have to do zone two training to induce adaptation there. You can also do higher intensities and still get improvements in fat oxidation.
- [20:18]
A
And I suppose one of the questions we might revisit later on and when we talk about some of the practicalities of this is for what type of people does it even become important to try and maximize fat oxidation and to try and optimize for the some of these outcomes? But one of the things that I did want to ask about was earlier you mentioned that first there's this unsubstantiated claim that we have Zone two is going to be the best for getting some of these adaptations. We can say that based on the evidence that is not an accurate claim sometimes. Then you said even we could have situations where someone is doing Zone two, particularly as a non athlete, and may not be getting not only not the best or the optimized degree of adaptations, may not be getting much adaptation at all compared to what people are perceived. Can you maybe just elaborate on this point of specifically in non athletes where we might be seeing this failure of adaptations at these types of intensities.
- [21:13]
B
So I think that data is more clear if we look at carbiorespiratory fitness or VO2 max. So there are a couple really nice studies, one out of University of Calgary and one from Queens from one of my colleagues here, where they look at different intensities of training and changes in VO2 max. And in those studies, it's really clear that the higher the intensity, the greater the adaptation, the greater the improvements. And in the populations that do either Zone two or three, like specifically, or do sort of moderate intensity walking on a treadmill five days a week, 30 minutes at a time, the mean changes are there, there are improvements, but they're much smaller than if you do higher intensities of exercise. So, yeah, so for general population, for most of us who are, you know, meeting physical activity guidelines around 150 minutes per week, we probably want to be prior. I think we want to be prioritizing intensity. And if we were to sacrifice intensity to do Zone two workouts, we're probably also sacrificing adaptations.
- [22:17]
A
Given that there's a lot of people discussing Zone 2 now and that can range from coaches to health professionals and so on, and maybe getting various pieces of input and have, let's say, a basis of understanding around what's going on. What do you think might be some of the areas of the literature that they are unfamiliar with that would be useful to know or what is maybe not appreciated about this whole area of research looking at these exercise intensities and some of the positive health adaptations we're looking to achieve?
- [22:47]
B
Yeah, I think that one of the things we were quite surprised at, again, Christy Storczyk leading this review, it was really hard to find studies that explicitly looked at the impact of Zone two. So we're able to find some studies, but there, there isn't a lot of research on the impact of Zone 2 training as I mentioned the, the studies we found kind of provided mixed results where, you know, some studies show benefits with Zone two, other studies don't, and maybe whether or not you see adaptation is dependent on how fit you are when you start training. But I think that would be the, the biggest message I would have is that people on the Internet are very, very confident in how amazing Zone two is. And in the scientific literature there is not evidence that supports that confidence.
- [23:36]
A
Like you say, that in of itself is striking that there's this a lack of data, even looking at some of these research questions that we care about, never mind to have any degree of confidence in some of the findings. I think in the review paper, you guys do a really nice job of laying out potential implications of this type of messaging and narrative. People may hear if they're basing certain types of extra size regimens on that. And one of that would be that someone could get to a point where they are solely focused on doing Zone 2 training at the cost of other modalities. And I think you really lay out well that this is not to say Zone two needs to be avoided or that's not beneficial, but rather to say doing this at the expense of all other modalities potentially could mean that someone is doing a disservice to themselves. Could you maybe talk to some of that and. Because I know it already ties into points you've already made.
- [24:31]
B
Yeah, I think that that would be just going back to those studies that for VO2 max, which is like the strongest predictor we have of all, cause mortality risk, functional capacity like health span, if you want to improve VO2 max, it's pretty clear that you want to be doing high intensity exercise. So if you're sacrificing, and again, this is specific to people who are doing three to five hours of exercise a week, if you sacrificing high intensity exercise and supplementing it with, or replacing it with Zone 2, you may be sacrificing improvements in VO2 Max, which, which again, like all exercise is good. So you probably not, it's not a huge risk or anything, but if you're trying to optimize and maximize health, you're probably sacrificing that maximization if you're taking away high intensity in favor of lower intensity exercise.
- [25:22]
A
And I mean, it's easy to imagine different scenarios in which someone could maybe get themselves into a situation where they are doing less exercise than they otherwise would. If they have this belief that, okay, I need to do Zone two training, that means I need to do A duration of a session that is sufficiently long enough, maybe I don't have time for that and I can't go out and do something shorter because I'll be wasting my time in zone three. And then suddenly you have someone that would have otherwise done some type of exercise and got a benefit from that now reducing the amount that may be doing out of fear of not doing it, quote, unquote correctly. That said, there's probably situations where some degree of zone two training is going to be useful for maybe things that don't relate to optimizing those adaptations, but maybe for more practical reasons. Could you maybe talk through your thoughts on some situations where you would see that more or less or a certain quantity of Zone 2 training would be useful for someone who's generally training for health purposes?
- [26:24]
B
Yeah, I'm going to come back to the point you made and this comes back to something I talked about earlier, about how different zone 2 is for different people. And you know, if you're going to go out and work out, you want to make sure you're getting a good workout. And for some people, for a lot of people, I think especially sedentary people who are starting to exercise, Zone two would, would be walking. And as soon as you start to jogs, it's probably true for me, I imagine as soon as I'm jogging, I'm above zone two. So if you think about it in that context, if we're actually telling people to go out and you have 30 minutes to exercise, but you need to be in zone two, that means you're just going for a 30 minute walk as opposed to doing a 30 minute jog. And I, I, I think when you think about it in that context, pretty intuitive that, well, the benefits are going to be better from the jogging, right? Not walking. And there are benefits from walking for sure, but you're gonna get more if you jog. So I think that's an important context and recognizing like for a marathon runner, zone 2 intensity is really fast, like they're running. But for the average person it could be a walk.
- [27:26]
A
Right. And I mean that, that has implications because they're like you say, those situations are so different. Given the need to offset fatigue with those athletes, Zone two is already going at a decent clip. But also we need to make sure of that over fatigue. With someone who's going out three, four, five times a week for health benefits, they're really not at major risk of fatiguing themselves so much they won't be able to recover in time for a jog. The next day. And so like you say, those contexts have to kick in at some point too. Yeah.
- [27:59]
B
And so to get back to your original question there, I think I'm aging and it's getting harder for me to recover from. I play hockey sometimes I the net the day after a game of hockey, I'm pretty sore and I kind of monitor that myself. And I feel like, yeah, I'm not going to go out and do a hard bike ride today because my body kind of hurts. And that would be the time where I would, I still want to do something. So I'll get on the trainer in my basement and do something pretty low intensity just to, you know, feel like I've still exercised but I'm not putting further stress on my body. So I think we can all kind of feel how we're feeling. And your body's not ready for more stress. You wanna avoid high intensity. And that might be a place for Zone 2 training in the general population. But yeah, I don't think we're other than that like feeling sore and feeling like you need recovery over training, overreaching. You have to be doing massive volumes to, to be at risk of that or of us don't need to worry about that.
- [28:56]
A
So if we were to presume a situation where someone is doing various types of training modalities with the goal of improving their metabolic health, generally staying healthy over time, cardiorespiratory fitness etc and they have the typical time availability that a lot of people may have of X number of hours per week to allot to that. Given that again, taking into account there's differences in what someone might adhere to, their preferences, all that type of stuff. But in general, is there something that as a broad recommendation we could generally say this would be a good starting point for someone if they are trying to get the most out of that X number of hours for that purpose.
- [29:36]
B
I mean my, if you're asking me, my answer to that is prioritize intensity. So if you're, whenever you're going out, actually it's a 30 minute jog an hour bike ride. Ride as hard as you can, work as hard as you can in that time that you have. If you're willing to do interval training, interval training is great. It's awful to do. But if you're willing to suffer for a bit, the benefits are, are definitely worth it. But yeah, just in general, like push yourself, go hard, you want to be a get high, accumulate as much high intensity volume as you can in your week. I think this is A really important point too, that to reiterate it is like if all you want to do, if all you enjoy doing is walking, that's amazing and I would definitely not discourage anybody from doing that. And, and if pushing yourself to jog starts to hurt your joints and makes you not want to exercise, then don't do that. Zone two is great if it's something you enjoy doing. And it's way better than nothing. It's just if we get into that question of what's optimal, that's where we want to start pushing intensity and getting away. Avoiding Zone two probably.
- [30:39]
A
And that's it of being aware of what those original claims around Zone two are. If someone makes a claim of, hey, you should start adding in more Zone two because it's easy to do, you're not going to get tired, it's not difficult, so you're, if you're new to exercise, it might be useful and it's just better than doing nothing. All those claims are very valid. Once someone starts going into the realm of you should do this training because it is better than any other modality and you will get the best adaptations to it. This is where maybe it starts to break down when we look at that literature. So with that, if we do turn to the research, you've already mentioned that we are very short of research on these specific types of research questions. For you looking at any of this stuff related to zone 2 or adaptations or otherwise. What are some interesting research questions that you would like to see answered in future research? Whether that's from a lab close to you or from others around the world. Are there any really interesting research questions that you think would be great next steps in this field?
- [31:39]
B
I think we could definitely use any studies like explicitly looking at the effects of Zone 2 training. So in our review we, we had to use studies that we thought were Zone two because people aren't prescribing Zone two specifically using that like lactate threshold cut point. So yeah, more research in general would be great, especially on mitochondrial outcomes. Personally, I think, I think it's really interesting that athletes are doing really large volumes of low intensity exercise. I think some of the stuff we've talked about today would suggest it's not doing very much for them. And then when you look at the research in athletes, if they want to improve their performance and VO2 max lactate thresholds, it may be requiring high intensity interval training to get those adaptations in athletes. But they're still doing these massive volumes. And so it could be maybe they're just they like being on their bikes, they like going for jogs, and they know they have to recover, so they're doing low intensities. But it's also possible that at when you hit a certain volume of low intensity, it starts to have beneficial effects. And potentially there's some, like, calcium signaling mechanisms or just utilizing fat, having flux through your fat metabolic pathways that could be beneficial. So I think those are really interesting questions, like trying to learn if we can, like, why are athletes doing this? Is it beneficial for them? Or is it just something they're doing because they're. They like being on their bikes?
- [33:05]
A
I think that's a crucial point of distinction for people, that it's really a question of why are we seeing these benefits? Because no doubt, as you said, there are elite athletes doing this that have huge success from it, measurable output as well, that they're improving. But of course, it's only one component of that training program. And so you have to start disentangling. Is it how much of the benefits they're getting over time is due to this big chunk, 80% of their training or whatever, from zone two or the other part that they're doing, or the combination of both. And then even if they're. We are getting that benefit, why is it happening and does that apply to other situations? I think all those things are useful, and I think what people are probably getting from your discussion is that these could be plausible and it's fine for someone to put them forward as ideas, but we then need to go and get research before we are super confident saying, this is exactly what's happening and this is what benefits someone's gonna get. Yeah.
- [34:03]
B
And is 20 hours of zone two the same as two hours of zone two? Because that's a huge difference in volume. And there could be benefits from 20.
- [34:11]
A
Hours that you don't get from two fascinating research questions. And sure that people will start pulling them up before we get to the very final question. For people who are interested in learning more about your lab or work that you guys have got going on, is there any places on the Internet you would send their attention towards or anything that you want to highlight to them at this point?
- [34:31]
B
Yeah. So they want to look up our lab. It's the Queen's Muscle Physiology Lab, and you could search that and find us there. I would highlight Christy Starstruck is. Is very active in social media and very interested in discussing these topics. I don't have a social media presence, but she definitely does. And so she would be a great person to Reach out to and look up what she's talking about.
- [34:51]
A
Fantastic. And for people listening, I will link to that in the description box and you can go and check those out as well as the review paper that we've mentioned throughout this episode. I do encourage you go and read that in its entirety. So with that, Brendan, we get to the final question. I always end the podcast on, which can be completely outside of what we've discussed today, if you wish, a rather broad question. So apologies. It's simply if you could advise people to do one thing each day that would have a positive impact on any area of their life, what might that one thing be? Yeah, that's a big question.
- [35:25]
B
I'll stick to exercise. I would just say move somehow every day. Yeah, if you can. If it's walking, I'm. As I mentioned, I'm getting older. I've started doing some mobility exercise and that's. That's making a huge difference for my back pain and my hips and. But yeah, just try to do something every day and, and make it enjoyable. Yeah. So if you like going for walks, zone two, maybe is the best thing for you.
- [35:47]
A
Perfect. Professor Brendan Bird, thank you so much for taking the time to, first of all, come and talk to me today for talking through your work and more broadly for your contributions to the field. It's been a pleasure to come and talk to you about this.
- [35:59]
B
Yeah, thank you very much for having.
- [36:13]
C
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- [37:50]
A
Or they could be a variety of.
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C
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- [38:05]
A
Can see all the details there.
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C
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- [38:17]
A
So thank you for that.
- [38:19]
C
I hope you do come back for.
- [38:21]
A
The next episode regardless.
- [38:22]
C
And until then, have a great week. Stay safe and take care.