Transcribed using AI transcription, errors may occur. Contact Mikki for clarification

00:03
Hi everyone, it's Mikki here. You're listening to Mikkipedia and this week on the podcast I speak to Professor Martin Gibala. So Martin and I discuss his work all about interval training in every manner of its use. We discuss the definition of high intensity, the metabolic and health benefits of high intensity training, and how to know if you're working hard enough. We discuss, you know, what different intervals are able to elicit.

00:32
We also discuss the value of activity in general, including the Zone 2 training, and research that Martin is involved in that explores the use of vigorous intermittent lifestyle activity. And this in itself can be a game changer for many people, especially if you're not inclined to be physically active. And of course, we also discuss sex and age-based differences and whether these are important to get the most out of time spent training, because there is a lot around on social media

01:02
you know, what we know about how women should train differently from men and what is known from actual human clinical trials versus mechanisms that might exist and how meaningful or otherwise that they are. I think you're really going to get a lot out of Professor Gabbala's chat with me today. He's super knowledgeable and is really able to translate that science into information that people understand. And this is really clear actually because

01:30
Of course he also has a book called The One Minute Workout, he's a co-author of that book that was released in 2017. For those of you unfamiliar, Dr Martin Gabala is a muscle physiologist and professor at McMaster University in Hamilton, Ontario in Canada. And he is what he would describe as an integrative physiologist, which is a super interesting term. He's best known for pioneering research on the health benefits of high intensity interval training.

02:00
in his profound understanding of HIT's physiological mechanisms, which of course we dive into today. As I mentioned, he's the co-author of the book, The One Minute Workout, and we've got links to both the book and how you can purchase it, and also Professor Gabala's profile, including his research papers, on the McMaster University page. Now before we jump on into it, I would like to remind you that the best way to support

02:30
the subscribe button on your favourite podcast listening platform because this increases the visibility of Micopedia in amongst literally thousands of other podcasts that are out there. And also while you're at it why not leave a 5 star review like all the other legends that have already done that. Alright team please enjoy this conversation I have with Professor Martin Gabala.

02:56
Martin, thank you so much for joining me this morning. I really appreciate you taking the time. I had the pleasure of listening to you in person last year on Kona talking about high intensity training and of course, had listened to several podcasts and am very aware of your research. So I'm looking forward to diving into the ins and outs of it today. Yeah, me too. Thanks for the opportunity. So can we kick off?

03:25
You're an integrative physiologist of human performance. I really love that term because I feel like so often in science, it's very easy to isolate areas almost distinct from others. Whereas even just that term implies that you think more than just about one area of the body or one system.

03:48
Yeah, when I was in graduate school, I had a professor who said, well, you're gonna have to pick the enzyme that you study for the rest of your career. And it didn't sound very appealing, but this area of integrative physiology certainly did. And so yeah, it's just that. I'm fascinated by how it sort of all goes together. And of course, exercise presents a massive challenge to integrative physiology. Many different physiological systems have to respond, your heart, your lungs, the blood vessels, muscles.

04:18
That was just a fascinating area of study for me, and I've always been very interested in it. And I've heard people say that if you could bottle all of the effects of exercise and put it into like a capsule or a pill, you would probably solve 99% of the chronic disease issues that people sort of face. And even looking at some of your research, which we're diving into today, it just feels like exercise hits on so many different levels.

04:48
for both people who, quote unquote, exercise, but also people who might just engage in some sort of physical activity with like that's not planned or structured. Yeah, absolutely. So, you know, physical activity is a very broad encompassing term. Exercise is a special sub-component of physical activity that, as you said, just refers to something that's planned and structured.

05:13
It's important to remember, I think, that we have physical activity guidelines. We don't have exercise guidelines for health. So there's many different ways that you can do it. And it's also a very encompassing way. You know, there's so many things are incorporated with physical activity. So I'm excited to dive into the conversation. So can we first, Martin, just get some of the basics down in how you define certain terms with regards to interval training, I guess.

05:43
is like a very broad term. I might be wrong about that, but can we sort of go through some of these basic terms that you work in? Yes, so interval training to me is just alternating bouts of more intense activity with recovery periods. We can talk about what defines high intensity in a moment, but it's just this idea of hills and valleys, going a little harder, taking a break, backing off and repeating that pattern over time. Now,

06:11
High intensity interval training, it depends if we're talking about physical activity for health or exercise for performance. So let's just talk about that health side of things. To me, and I think to many colleagues working in this field, high intensity means vigorous intensity effort. And that's very well defined in the public health guidelines. We'll often hear this, high intensity is 80% of your maximum heart rate.

06:40
well that's a reasonable guy using one metric, but we like to think of a more all-encompassing view of interval training, and there's many different ways to define vigorous intensity effort. So on a 10-point scale, the World Health Organization would define that as a seven out of 10, where zero is lying on the couch, 10 is sprint from danger pace, so we're talking about a seven. The American College of Sports Medicine would say, yeah, that's about 77% of your

07:10
maximum heart rate. So that's what we mean on the health exercise prescription side, but athletes of course talk about domains, moderate, heavy, severe intensity exercise. And so high intensity means getting into that severe intensity domain, typically above critical power or your second lactate threshold. So I like that approach of using different.

07:36
ways of defining it, which I think you can tailor to your specific interest, whether that's performance or general health. Yeah. And I think of people listening, I think they're probably less aware of its use in health, actually. Because if I think about interval training, high intensity training, I think about exercise classes, I think about particular sessions I might do as part of my marathon training that would sort of fall into those domains.

08:06
for someone who might just be an active individual, but doesn't engage in that structured exercise, they probably haven't even sort of thought about that actually before. Absolutely. There's a figure that I like to show in a lot of my presentations, but it's really compelling. And what it shows is two heart rate tracings of individuals on very different ends of the fitness spectrum. The one heart rate tracing is from an Olympic athlete and the lower tracing is from an individual who has heart disease.

08:36
rehabilitation program. They're both doing the exact same high intensity interval training protocol and it's eliciting about 80% or 90% of their maximum. But of course for the Olympic athlete, this is very hard running on an incline on a treadmill. Whereas for the cardiac patient, it's basically interval walking. So it's really a striking example of what you're alluding to and that's that interval training.

09:04
has been so widely applied to different individuals on various ends of the fitness spectrum. And I think in some ways we've done a disservice. People think about high intensity interval training. They picture that hardcore athlete sprinting as hard as they can. And they think that's high intensity interval training, but it's not. That's one type of interval training. It's very potent way. But again, interval walking counts. There's many different ways to do this.

09:34
It's been so widely applied to older individuals, people with metabolic syndrome, type two diabetes, hypertension, metabolic syndrome, and many different heart conditions as well. Yeah, I feel like the way that you describe how the WHO defines it using a rate of perceived exertion, potentially, that then makes sense because then it's relative to the individual undertaking it rather than some sort of objective.

10:04
of things outside of the individual, I guess. Absolutely, it's relative intensity for you. And I believe that perceived effort is a really good way to go. Martin, how many people, I don't know if you know, I mean, if anyone's gonna know, you will, how many people engage in vigorous activity? Not as many people as we would like to. So if we look at what...

10:28
The physical activity guidelines that WHO is suggesting we do generally, and you know this, it's 150 minutes a week of moderate physical activity, 75 minutes a week of vigorous, it varies a little bit by country. So the traditional view would be based on survey data.

10:51
uh... and and those would suggest that very few people maybe five percent or so are engaging in vigorous physical activity i think there's a newer data that's using accelerometers that would suggest no no that maybe more people than we and we think are actually engaging in in physical activity uh... but clearly you know we would like to have many more engaged in invigorates uh... physical activity any type of physical activity moderate to vigorous but

11:19
you know, a through line of our research has been, you know, every little bit counts, right? And so we hear these simple messages, and you'd be aware that the most recent changes to the physical activity guidelines around the world generally removed a previous requirement that activity had to be 10 minutes in duration to count at all, because there was never any really good science behind that, and it dovetails with this emerging work showing that even a few minutes

11:48
daily activity can be good for us. And if it's vigorous in nature, as we've defined, it can be markedly beneficial. Even a few minutes a day can really lower our risk of mortality, dying from all causes, cardiovascular disease, type 2 diabetes, many different conditions with only a few minutes a day. Yeah. And I'm really looking forward to chatting to you about one of your research papers that looks at that vigorous...

12:15
But a question I want to ask you, Matt, and I ask a lot of my exercise people this, because I'm just curious as to your thoughts. I feel almost in despair when I look at the numbers of people who engage in physical activity as defined. Of course, I am biased because since my teenage years, I've been an active individual and it's how I couldn't imagine living life any other way. Structured leisure time activity, I sort of do it all.

12:45
And I just, it baffles me that people, like the information is there on the health benefits, yet people for whatever reason just don't engage. And I'm just really curious to hear, you know, whether you feel sort of similarly despair or you actually, I suppose your work looks specifically at people who don't engage in those guidelines yet, of course, do other things which we'll talk about. But what are your thoughts? Yeah.

13:13
I do feel, I wish more people were active. You know, I'm an exercise physiologist who focuses more on physical health and the physiological systems, but of course the work that many of our behavioral colleagues is most important. You know, how do we cue people to engage in this type of activity? But it's a real challenge. So I don't know that I have despair. Certainly I wish more people

13:40
were active, I think in some ways that's related to people don't necessarily see the value in how little you need to do in order to move the needle on things like, you know, all cause mortality, you know, risk of dying. That's a very scary term, but we're talking so little and, you know, what we want to do is just move people out of that. Just don't be in the lowermost zone, right?

14:07
move out of the lower most zone. And so now in talks, I'll try to put relative risk in context. So we can say that if you can boost your fitness by about 10%, the health improvement and the risk reduction associated with that, it's like losing two inches off your waist or five centimeters off your waist or about a five point drop.

14:33
in your blood pressure and people start to resonate with, okay, measuring those sorts of things in the doctor's office. Unfortunately, we don't have a good way of measuring fitness really, really easily, like we do blood pressure, body temperature, or things like that. But as you'd know, there's been a lot of calls to make fitness a clinical vital sign. And so I think maybe trying to get that message across that fitness is really, really important for...

15:02
all of these conditions, including things like your mental health, dementia risk, all of those. And it doesn't take a lot to move the needle to have these profound benefits. So as my colleague Sue Phillips says, people don't value the time associated with physical activity to see the benefit. It's not really that I don't think many of us have time in our day to get it in because it's not that much when you add it up over the course of the week.

15:31
People aren't seeing value in that, you know, to say nothing about social determinants of health and a lot of us just don't, a lot of us, you know, have opportunities that other individuals do not. Yeah, and this is where I love the work that you're doing and collaborating with others on is that eventually at some point in time, that notion that if you don't have even 20 minutes or 25 or, you know, that almost...

15:59
athlete mindset of if you can't, you know, if you don't have 45 minutes to do it, then it's not worth doing. Like this is where a lot of your work is just so impactful. Yeah, bingo. No, I appreciate you saying that, but you know, I do think a through line have our work has not been at all. And some people have misinterpreted and say, well, you're challenging the public health guidelines. No, we're not. We would like everyone to meet the guidelines. But we're trying to ask that question of, okay, well, how low can you go? Let's meet people where they are.

16:28
And we know that there's massive benefit with the guidelines if you'll do it, but a lot of people are choosing not to for lots of reasons. And so let's say, okay, you got a minute in a day, you got a few minutes in a day, you have 10 minutes three times a week, and trying to show from a physiological perspective, these are all the beneficial changes that you can see. This is how it translates to some health related metrics, your insulin sensitivity. And so let's start.

16:56
there and try and meet people where they are. We know that time is an excuse for a lot of people. It's not really lack of time. And many behavioral specialists will remind us of that. We fully recognize that. But the reality is most people are choosing not to engage for many reasons and time remains a cited barrier for a lot of people. Yeah, for sure. And Martin, are you and your colleagues in

17:26
with those people who set guidelines and because guidelines are so quick, no, they're so slow to move, aren't they? Like they take years and years and years for sort of subtle changes. But if more of the message of your work was inserted into there, I feel that a lot of those barriers could be removed for people. Yeah, so my perspective on this has really evolved. And what I mean by that is I certainly have a much more fulsome appreciation for

17:55
the level of evidence that goes into the guidelines, right? And so what we, there's just such compelling data, epidemiological data to show that if people do this amount of physical activity, you know, the classic 150 minutes a week, that's associated with reductions in all-cause mortality, cardiovascular disease mortality, cardiovascular disease risk. We just don't have that level of evidence

18:25
to interval training, but again, rather than suggesting it's an either or, okay, well, the classic guidelines or HIT, it's reminding people, no, no, HIT can fit within the guidelines. So it's a way to help achieve the guidelines. And also in our own work, we're trying to, like a lot of our work has been what I call proof of concept ideas, trying to get these ideas out there, doing small scale studies, but we've tried

18:53
especially over the last couple of years, to start engaging in more randomized clinical trials, collaborating with individuals on larger multi-center trials, and then collaborating with some individuals who are doing work much like I don't do, large-scale epidemiological studies. And some of those individuals are actually at the table involved in writing the physical activity guidelines. So I would say we're trying to engage on multiple fronts.

19:23
not trying to be preachy at all, but just try and move the needle with our own work and collaborate with those who are in an opportunity to maybe move forward on other areas. Exercise is such a powerful tool to improve an individual's self-efficacy and confidence in that space. And I feel like with...

19:48
the work that you do showing and we'll talk about the vigorous, I can't remember what VILPA stands for. I literally just looked at it five minutes before we jumped on the call. Yeah, we'll get to it, but it's Vigorous Intermittent Lifestyle Physical Activity. Just what we need another acronym, I know, but we'll break it down. Yeah. So I feel like, you know, if people feel that they can get...

20:11
They see the benefit from doing that. That's just going to transform them where it's really important in that mindset piece and maybe then have more of a likelihood of then wanting to do some more activity that might fall more into the traditional guidelines, for what it's worth. I don't know. I agree. We're both practicing exercise behavior here without a license. Yeah, actually. In talking to my behavioral colleagues, and again, this is where I've tried to learn.

20:40
a lot. I think generally speaking there's two schools of thought and I would say the more traditional school of thought is well if physical activity is uncomfortable, people will find it aversive, they're unlikely to do it, but there's a whole other school of thought and many exercise behavioral people are working in this space saying no, no, wait a minute, continuous vigorous exercise is unlike.

21:08
intermittent vigorous exercise, especially if you don't have to do very much of it. They're conducting this research to show actually measures of affect and adherence are very similar between HIIT and more traditional moderate intensity continuous training, or at least it's sort of different strokes for different folks. We're also trying to talk about expanding the movement menu. We...

21:35
We might have a standardized diet that we generally stick to foods we like and dislike, but we still don't want to eat that all the time. And so when it comes to exercise and physical activity, can we give people other options to choose from, either because they find they really like that option or they're going to sprinkle that option in once in a while? Because to your point, a lot of people still think, okay, exercise, physical activity, it's this thing that I need to do.

22:02
in a special place after I change into special clothes, and it's going to take me 45 minutes or an hour. And so it's easy to blow that off. You're like, that's too daunting. But it's reminding people, you know, no, no, a few minutes, all activity counts. That messaging is really important to reinforce. Yeah, there was a great paper last year. I have no details on who the authors were that looked at the...

22:26
doing 10 squats, I believe, every 45 minutes, and the impact that had on blood sugar levels and blood sugar control across the day, showing how beneficial it was, and it was akin to, I don't know, maybe it was three times 10-minute walks or a half-hour bout. Those are such good examples of how effective it can be.

22:48
Yeah, Dr. Edward Coyle down at the UT Austin is doing some similar work when it comes to cycling. And these are four second sprints on a bike every hour or so. And so it's not necessarily practical and it doesn't have to be jumping on a bike, but it could be a few seconds of stair climbing every hour or so. So it's along the same line that it doesn't take a lot, but if you repeat it consistently, it can really pay benefits. Yeah.

23:16
Martin, I have to be honest. I come from an endurance background. I have, you know, as I'm now I'm older, I am slower. And what appeals to me more is just constant movement, actually, like I don't like hurting. I mean, I do like in running, like if I'm doing efforts, I get in it and I enjoy the challenge. But I don't think that the type of work I do is anywhere near the type of intensity that might fall under something like sprint interval training. Like...

23:45
Am I doing myself a disservice by absolutely ignoring sit and just going into my moderate to high? What's your thoughts? Yeah. So I guess I would ask, why are you training? And so I think, and again, you would well know this, any serious endurance athlete who's competing for performance, where performance is their primary goal, they're going to incorporate high intensity intervals. And it's the classic.

24:13
80-20 split in terms of traditional moderate low intensity training, 20% high intensity slash intervals. But that doesn't mean that you have to do that. And so again, the question becomes, what are you training for? If it's more about, I just enjoy being active on a regular basis. I like engaging in my sport. I don't care if I'm middle of the pack anymore. I don't want to get hurt, right? I certainly don't want to.

24:42
sprint on old knees, bounding up these hills, and I may injure myself. So I'd say that's the first question is, why are you doing this? And if you're otherwise engaged in physical activity, you're enjoying it, just keep doing it. Oh, that's nice. You've actually just given me permission to absolutely live in that gray zone. And who doesn't love the gray zone? It's just that perfect amount of hurting just a little bit, but not so much that you are

25:12
overly uncomfortable. Actually, I do have a question on the... They've got a lot of classes nowadays like F45 and Orange Theory, and I guess CrossFit may fall under this as well. And they're often... They get bashed actually on social media as being inappropriate for women over the age of 40, or that's actually typically the group. Perimenopause, postmenopausal woman should not be doing this activity.

25:42
What are your thoughts on those types of classes? Yeah. So I, I, I generally dislike hard and fast rules. And, you know, I tend to be that cautious scientist where, you know, every question you ask is, well, it depends, but, and, and, and, which is not great in interviews like this, because people say, well, I just want to know the answer. Quit hedging. Uh, but so I, I think, you know, to make a blanket statement that, um, females or post menopausal women, uh, you know,

26:10
High intensity exercises contraindicated for them. No, I don't subscribe to that at all. And I think there's a lot of evidence to suggest that's not the case. I think here now the devil's in the details, right? So what type of vigorous intensity effort are you doing? Is it box drums? Is it sprinting up hills? Or are you doing vigorous exercise on a bike or an elliptical machine or in a pool where it's much more...

26:38
uh... joint friendly so it it really depends on the type of exercise and the specific uh... in intensity but i think a lot of these programs group fitness classes are uh... are are based on a lot of good principles i think where people can get themselves into trouble is are are they competing just against themselves or do they see that individual to people over who they really like to beat

27:04
or there are heart rates on the screen and it's not exactly where the trainer's telling them they need to be, maybe that's because their age-predicted maximal heart rate is actually quite low. So I think that's where people can get into trouble where the activity is inappropriate for them either because it's the specific intensity, the specific activity they may not be suited for. But otherwise, interval training is widely applicable to so many individuals.

27:31
Yeah. And I guess as well, it's knowing yourself and knowing the recovery, because that's where things have changed as I've aged and I'm probably for you as well. Like the older you get, just you need more time to get over those types of training sessions where when you're in your 20s and even 30s, so it's just so much easier to sort of do.

27:51
No, exactly, right? I'm 56 years old now, right? And I still do a lot of interval training, but I can't run anymore. I'm that classic individual with an old sports injury who has knee osteoarthritis. So I can hike forever, but I can't run more than about 100 meters without being in debilitating pain. But I can cycle very hard. I can still play ice hockey. I can do other forms of vigorous activity. Anytime I swim, I'm not a...

28:19
good technical swimmer. So any type of swimming is an interval workout for me. So again, it really depends on the specific activity as opposed to a generic, you know, hit yes or no for someone. Yeah. And Martin, what is the difference between hit and sit? And is sit more applicable to post-menopausal woman compared to hit? Or is that yet another context specific situation?

28:49
Yeah, so I guess two things there. You know, getting back to this way that we define high intensity interval training, you have the health context, you have the performance context. We would suggest that SIT is getting into this near maximal to maximal effort range. And so for example, the American College of Sports Medicine would define that as above 95% of your maximal heart rate.

29:16
If you're talking about exercise intensity domains, the upper echelon of the severe domain is termed the extreme intensity domain. Generally, these are workloads above maximal aerobic speed or above VO2 max pace. So these, you know, it's the very upper end, whatever your zones are, if you're using a six zone system, it's zone six, it's the highest level of.

29:44
of effort. And so I would say that type of effort is not necessarily appropriate for everyone. And while I think high intensity interval training can be widely applied, sprint interval training, you need to, you know, the older you get, certainly, I think we need to use a little bit of caution there. And so I wouldn't suggest that sprint interval training is particularly ideal.

30:09
for postmenopausal women. Certainly, I think they can do high intensity nerve training. Some may be able to do sit, and it's appropriate for them, but I would suggest some caution with the very intense stuff, particularly the older we get. Yeah, and is sit, because it's a subset of the high intensity training, like is there, like do you, I know you're very,

30:37
broad and accepting of a wide range of hit-based activities. But if someone asks, so what is the specific dose that I would need in a week to see the health benefits? And what should that look like? How do you answer a question like that? Yeah, so we do know, we have evidence to make some informed opinions there. And so again, to clarify, if we're talking about that 0 to 10 scale, 7 to 10 would qualify as hit.

31:06
910 would be the sit range. So it's the upper end there. So that's the sort of the level of effort that we're talking about. And we have done studies on this where we've shown as little as three 20 second efforts. So that's where the title of my book, The One Minute Workout comes from. It was based on that research that had looked at as few as three 20 second efforts. A few times a week, we can see measurable improvements.

31:34
in VO2 max or your cardiospiratory fitness, measurable improvements in markers of insulin sensitivity, other health related metrics. So the answer there would be a few minutes of sit a week can be extremely potent and efficacious to move the needle there on these fitness and health markers. But again, it's not necessarily for everyone. Yeah. And I, to be honest, I wouldn't know how to work that hard, actually.

32:04
Literally, if I think about myself running, my heart rate tends to be run a little higher than what you might read in textbooks and stuff is appropriate for someone of my age. But it's always been that way. But then if I'm on a bike, for example, where I might feel most confident at trying some sit because there's less risk of injury, there's just no way that my heart rate almost reflects the effort I feel I'm putting in.

32:33
What happens there? Yes, so definitely there's a lag in the cardiovascular response. And so there's a classic exercise test called a Wingate test. It's a 30 second all out, as hard as you can go sprint on a very specialized bike. The pace we would use is sprint from danger pacer. If you can imagine, if you have children or a loved one, you're pedaling this bike as hard as you can to save them.

33:02
from an oncoming car or to get to them as fast as possible. That's the level of effort we're demanding. But if you do 30 seconds of that, you're absolutely gassed, but your heart rate might be 70% of maximum because it lags behind. It's gonna go up in recovery. And if you certainly repeat those sprint efforts, you'll get close to your maximum heart rate. But to your point, you can work very, very hard in some of these traditional measures like heart rate.

33:29
they may not track very well. And that remains, I think, a problem with the translation of this type of exercise and why we're sort of coming back to, RPE is probably our best metric for individuals as opposed to some of these more traditional objective markers. Yeah, that's nice. And I remember when I was young, like when I'd just started getting into the gym, my gym would do fitness tests free for us. And like I would, five days of the week, I'll be at circuit class.

33:59
working my heart out and getting noticeably fitter. Then I would jump on this fitness test and I would, oh, I'd fail. I would fail every single time because my heart rate didn't do what I expected it and what was expected of it for someone who was getting fitter. And it was so demoralizing actually. It is, and we, you know, I think many people are familiar with these, you know, 220 minus your age metrics to sort of estimate your maximum heart rate, but it's important to remember one, it's just an estimate.

34:27
And it would be very good if we took 100 individuals who are 40 years old, on average, we would see 180 beats per minute as their maximum heart rate, 220 minus 40, 220 minus their age, but there's massive variability around that. Some individuals, their maximum heart rate might only be 160 or less, and others, it's gonna be 220 or more. And so, you know...

34:51
where you fall individually to your point, you can dramatically over or underestimate your actual training, which can be very frustrating for those on the lower end of that spectrum who are being told, you're not working hard enough and they feel absolutely gassed because they have nothing left in the tank. It's just their tank isn't as big as someone who has a very big maximal heart rate. Yeah. Oh man, I wish I knew that like 30 years ago. I would have thought a whole lot better.

35:20
Madhav, now we sort of briefly, you mentioned insulin sensitivity just as part of your conversation around HIIT. Can we discuss what particular benefits, like what are those physiological benefits from doing that interval based training, be it HIIT, SIT or like? Yeah, so I'm classically trained as a skeletal muscle physiologist and so I always go to muscle first. Clearly it's really important, but it's not everything.

35:50
improvement in insulin sensitivity is likely due to changes in your skeletal muscle probably related to the in likely increased mitochondria so it's a real point of contention right now of whether the improvement in insulin sensitivity is due to the increase in mitochondria or whether the mitochondria just are.

36:15
they change at the same time and it might be related more to how your body handles and breaks down fatty acids and this gets into some complex molecular signaling. But suffice to say mitochondria are these specialized components of your muscle, often termed the powerhouses of the cell, but they're called that because it's the site where

36:38
Your muscles use oxygen to burn sugars and fats to produce energy aerobically. It's a very efficient way to produce energy. And we know that as your mitochondrial health improves, your mitochondrial content, it goes up. That's associated with lower risk for type two diabetes, better insulin sensitivity. And so it's clearly related in part to these beneficial changes in your muscles that allow it to.

37:07
to burn sugars and fats better. But there's clearly other areas involved. The blood supply gets better. Your liver is clearly involved in insulin sensitivity. So there's many components of the body that are likely involved. Muscles likely play an important role, including in their ability to take up sugars and fats. So they clear them out of the bloodstream better than they would in a less trained state. Yeah.

37:34
And I find it interesting the conversation around mitochondria and exercise, because you hear a lot that its zone two training improves and increases mitochondrial biogenesis to the point where you just say it. Like even a couple of weeks ago, I'm like, oh yeah, zone two, that increases mitochondria. And then my friend and who I think works with you, Christy, is like, she's like, where's the evidence for that? I'm like, oh, very good call. She called me out, and rightfully so. So.

38:03
Can you Martin, like what is the state of evidence around different exercise types for improving mitochondrial biogenesis? Yeah, so number of layers to this question, but I think number one, zone two has, classically in a three zone model, zone two was that heavy intensity domain, but it's sort of been, I think many influential podcasters in that have now.

38:30
Define zone two, it's clearly become widely known as this lower intensity just below your first lactate threshold. It's associated with continuous long duration, moderate intensity exercise. Getting back to that classic 80-20 split that high level athletes were engaged in, the suggestion is well, that's optimal for everyone.

38:57
So if you're training 30 hours a week, if you're doing the guidelines, if you're doing less than the guidelines, 80-20 is the right mix. So 80% low intensity or quote unquote zone two pace and 20% high intensity or quote unquote VO2 max pace. It's a fine suggestion. We need many people to just be more active, but to suggest in my mind that zone two is

39:25
I just don't think the evidence is there to support that. And we know that there's many ways to boost your mitochondria. To my mind, I think more vigorous exercise is actually a more potent way to improve your mitochondrial health. So low intensity, long duration, it can absolutely be fine to increase mitochondria, but to suggest that it's optimal, I just don't think the evidence is out there.

39:53
to make claims like that. And you see these sweeping generalizations that I think are based on how high level athletes train. And I just don't think it's applicable to many individuals, especially if you're only training an hour or two a week. Yeah, no, for sure. And Martin, are there any sex-based differences in how females and males respond to interval training that then makes one

40:23
type of training better than the other? So there's definitely biological sex-based differences in responses to exercise. I don't think there's compelling evidence to suggest that there's one type of interval training that's better than the other, or even one type of exercise that's better than another. Some of our work has hinted or suggested some sex-based differences, but they're very subtle overall. And so I think

40:53
The way that I like to think about is the inter-individual variability in exercise responses is huge. And so it's much greater than any clear biological sex-based differences. So the takeaway there, there might be some subtle differences. I don't think it has a massive impact on how people train. Both biological males and females can benefit from interval training.

41:21
the suggestion would be like we said before, do what you like and enjoy, and you're more likely to stick with it, I don't think there's evidence to suggest you should train particularly this way based on your biological sex. Yeah, okay, nice one. Now, if we think about your paper on vilpa, to get back to that term or acronym, and you'll need to remind me again what that is. Sometimes you just have it and then it's just, there's no way I'm actually going to.

41:48
keep that in my brain. But can you chat us through, I guess, what you were, the actual paper that I was reading and the research that you did in the space? Give us the broad overview. Yeah, absolutely. So again, so the VILPA is vigorous. So now we have a good understanding of what vigorous is. Intermittent as opposed to continuous. Okay. Lifestyle, physical activity. So

42:12
Not structured exercise. This is activities of daily living just as we're going about our day. And so classic examples of VILPA would be running briskly for the bus or the subway. You're gonna be late, so you gotta go. Coming into the office in the morning, or maybe if you live in an apartment building, you have to get to your apartment or your office on level three. You could take the elevator, you could take the stairs.

42:37
stairs would likely engage in about a vilpa, because even if you're quite fit, you know, you rapidly ascend the stairs a little bit. Getting off an airplane after a long flight, same thing, you have your luggage, you can take the escalator, or you can, you know, use the stairs. Playing with your children in a vigorous manner. All of these things are examples of where physical activity can be embedded into our day. This is not structured and planned exercise.

43:06
but we choose or we can choose to engage in it in a vigorous manner. And so this work that we're talking about very much led by a colleague, Emanuel Stamatakis, out of the University of Sydney in Australia, but it mined the UK biobank data. So this is a very large health database in the UK and you're able to look at very large numbers of individuals and make associations. And so in this particular study, it followed

43:33
a group of 25,000 individuals over a period of seven years. They wore accelerometers for periods of time, which was able to say, okay, they were engaged in moderate physical activity, moderate intensity physical activity, vigorous intensity physical activity. And then it was able to make some associations between dose and health outcomes. And what it showed was...

43:59
Even a few minutes a day of vilpa, we're talking three to four minutes a day of unstructured lifestyle physical activity, three to four minutes at a vigorous effort was associated with marked reductions in risk of dying from all cause, 25 to 30% reductions in all cause mortality, larger reductions in cardiovascular disease mortality. So literally we're talking here.

44:27
20, 25 minutes a week of vigorous intensity physical activity spread out throughout the day periodically marked improvements to health profiles. And that's Dr. Stamatakis is now showing that in multiple studies with a number of different colleagues and collaborators. Yeah. So, which is like, those are like quite stunning results for what, you know, for the

44:54
question that was asked, you almost never see that kind of dose response relationship. But it's been replicated, is what you've just said. Absolutely. And the important thing in that study that we were talking about that I was part of, these were in self-identified non-exercisers. So these were people who didn't consider themselves exercisers. They certainly didn't build in structured exercise other than maybe a weekly walk into their life. And they still saw this. And as part of that paper,

45:23
it was repeated in individuals who considered themselves exercisers. So this is a very robust finding. It doesn't imply cause and effect. That's the thing when we look at these epidemiological studies, but you're starting to see a pattern here. These small-scale studies looking at biological mechanisms, these larger epidemiological studies, and in between randomized controlled trials, all pointing in the same direction saying, know what?

45:51
There's something about vigorous exercise that it's particularly beneficial for us when we do small doses. And Martin, were there differences between those people who exercised versus those self-report non-exercises in terms of health risk? Yeah, just the way this study was set up, you couldn't definitively answer that question. I think generally we would associate the people doing greater amounts of physical activity and structured exercise to probably have...

46:19
higher things like their overall fitness would be higher, but that wasn't a specific point in that study. But I think the notion that it still was beneficial in people who exercise, you'd be familiar with some of these data. Meeting the guidelines is great, but we also wanna break up sedentary behavior through the day. So it...

46:43
it's not enough to just largely sit for 23 hours and then get your one hour workout in, you're gonna be much better off if you can build in some activity breaks as well. And so, even for us exercise physiologists who are quite committed to our daily exercise, it's important to remember, you know what, I gotta get up from my desk and go for a walk right now, or just stroll around my office or take the stairs just to break up all this sedentary time. Martin, you mentioned accelerometers, can you just tell people what they are?

47:12
Yeah, so generally these track movement. So they're devices that can track essentially speed of movement. And so it's a way to capture small changes and patterns of physical activity. And then you can analyze these data and break it down in a moderate vigorous physical activity. And so it's a more objective way to capture that. These are usually worn on the wrist or on the thigh sometimes.

47:40
But there's a way to capture literally the accelerometry, how quickly individuals are moving and break the knees into bins of light, moderate, vigorous intensity, because many of the traditional associations are based on self-report or training diaries, where individuals are recording information in a booklet. These are a more objective way to try and capture that, and importantly, small.

48:08
very granular details into a short bout of, for example, vigorous physical activity. Yeah, for sure. Like, I mean, there's no way that anyone can capture in a journal that you ran across the road to get the bus or, you know, walked up some stairs and, you know, you just don't even think about it. Exactly. And that's what these data are being able to, you know, in part, I think how they're able to advance is...

48:33
capturing these small granular changes in large numbers of individuals and then associating them with health outcomes. Martin, you mentioned, obviously I asked you about the potential health benefits of the HIP-based training and what you mentioned there with the mitochondria, insulin sensitivity, changes to sort of the musculoskeletal system. Are these the mechanisms that work here, you think? In part.

48:59
We also know the whole oxygen delivery side of things is very important. And so if there was one thing that determines your VO2 max or your cardiospiratory fitness, and VO2 max is just the objective measure of cardiospiratory fitness, the biggest thing that sets all of us apart is the ability of our heart to pump blood. So our cardiac output, our stroke volume, which is literally how well your heart squeezes blood out of it every beat and every minute.

49:29
So the delivery side is also very, very important there. How well your heart pumps blood, how well your lungs oxygenate the blood, and how well the blood vessels dilate, how elastic the blood vessels are to allow the blood and oxygen to flow to the muscles where then it's utilized. So getting back to that's the integrative physiology and why it's such an interesting area to study, because all of these things, they're sort of like gears, and they all have to turn together at the same rate.

49:59
to optimize your health. And if you have one gear that sort of stuck or turns quite slow, that can really affect the overall system of that rate of oxygen flow through the whole system. Yeah, for sure. And just to clarify, with this particular study, when you looked at other lifestyle factors such as smoking, alcohol, biological sex, sleep, there were no differences in those sort of buckets?

50:28
That's right. And this is more the domain of some of my expert collaborators on that, but exactly. So you try to control for these other potential confounding variables so that you can just try to look at the specific variable of interest, in this case, physical activity and how much of it and what intensity it was performed at. Yeah. And I have to say, like, when you look oftentimes at large data sets like this, the

50:54
potential, the significant finding is often a very small number, but because of the volume of people in there, it's almost like you've got enough data points for it to be significant. But here, it was just such a drop in risk, which was, I think, super interesting. Yeah, absolutely. The risk reduction, to your point, was very large and it would be very meaningful in real life. Yeah.

51:22
Has your work in this area changed your habits around exercise? Maybe it has reinforced things that I was already doing. I'm often asked, how did you first get into this field? My answer is it was twofold. There was a personal interest. I was a young assistant professor. I had a working spouse. We had two young children at the time. Quite ironically for an exercise physiology professor, you don't have a lot of time to be active. And so...

51:51
I was incorporating interval training because I was aware, you know, even 25 years ago of the benefits because, you know, we tend to rediscover this. You know, many smarter people than I have been doing this for a long time. And that dovetailed with a professional interest in that I've taught a course called the Integrative Physiology of Human Performance for a long time. And I would ask my students, you know, why do marathon runners or why do these high level aerobic athletes incorporate sprints?

52:19
And it was a way to introduce the underlying biochemistry and you frame it through an athlete prism. They're often interested in that. So I would say I've always been interested in this way, personally, of maintaining my fitness and health or trying to. And the work that we're doing and many others is just reinforce that messaging, the value of vigorous effort. Yeah, do you think it in any way replaces things

52:49
leisure activity like walking and things like that? No, I think, and my advice to people would be try and do it all, right? And so even though I'm sort of, I am clearly a proponent of interval training, I like to go for a walk with a dog or my wife as well, or sometimes just take a long hike. So I think ideally we'd like to do something slow to moderate for a long period of time.

53:19
Huff and puff a bit sometimes, so work hard once in a while for short periods. And of course, make sure we're incorporating some sort of resistance exercise as well. That doesn't mean throwing away around heavy weights at the gym. There's lots of ways to do body weight style exercise. And of course, try and get your flexibility in and all of that and your proper sleep. So follow the guidelines ideally.

53:43
Yeah. You've just like, now, where am I going to find that two hours? I was feeling quite hopeful that four minutes is enough. Martin, you hear a lot about snactivity in terms of doing bodyweight training, like press-ups and push-ups. I mean, I like to do stuff like this if I'm at the airport waiting or on a plane. You go to the toilet cubicle and you do some squats or whatever. Does that count as any sort of interval-based training or because it's more like...

54:12
Yeah, how does that fit in? Yeah, great question. And I think this is where, again, if you take an all-encompassing view to interval training, it can be more aerobic, card it can be more resistance, strength-based. And so bodyweight style training or classic calisthenics are sort of in the middle, right? So I definitely think it can count as a style or form of interval training, especially if you keep recovery periods short.

54:41
you do a minute of burpees or air squats or pushups or lunges, a short recovery period, and you repeat that or you choose a different body weight exercise, absolutely I think that counts. And it can have a dual benefit. You get the cardiovascular conditioning, but you get some muscle strengthening effects as well. And so these, yeah, these hotel room workouts or travel workouts, just a tremendous way to train, I think, and at least maintain your fitness, both strength and aerobic fitness.

55:11
during periods where your options are limited. Yeah, nice one. I mean, I don't think burpees are in my future, but everything else that you mentioned sounds really good. And what I really love, Martin, is what you said initially at the start of the call. A lot of this stuff may feel daunting and hard to someone who is yet to engage in physical activity, but as you said, it's relative to where you're at.

55:39
So even if you are literally doing nothing right now, even the walking, which actually, to your point, like you get a... I had a colleague, Mark Cucazella, did a presentation on insulin resistance and people who were very unfit. And even you said just getting off a couch is like interval training to them. And that's reflected in their blood parameters and their lactate and stuff like that. But you can just start where you're at.

56:08
Absolutely, we'll just tell people, you know, get out of your comfort zone a little bit. And again, interval walking counts and there's good data. It sounds so simple, but you know, if your only exercise is walking down to the mailbox or around the block at night, picking up the pace for a few light posts, then backing off just these gentle hills and valleys, there's randomized controlled trials, compelling data to show that actually the interval walking approach is better for you in terms of your fitness.

56:38
your blood sugar control, and so any type of activity, good, but interval walking, tremendous, right? And so it's very widely applicable, including studies in frail elderly individuals, where you can see that it improves some of their lower body strength as well. So I think just it's another compelling example of this general style or approach to physical activity. It can just be scaled tremendously to almost any starting level of fitness.

57:07
Yeah, nice one. So Martin, what is on the agenda for you over the next couple of years? What should we expect from your lab? Yeah, so we're interested in this area of exercise snacking. You know, an exercise snack to us is what that means is a bout of activity that lasts one minute or less, but is performed with vigorous effort. And so we have some multi-center randomized control trials ongoing right now where we're

57:35
collaborating with a number of experts including behavioral specialists, some industry partners who have come up with a smartphone app. And so how we're delivering this intervention is, again, meet people where they are. So they get a text that says, hey, time for your exercise snack. They look on their phone, it takes them to a video, says today your snack, you have these snack options. Which one would you like to do? We'd like you to do 20 of these snacks a week.

58:02
So four snacks five times a day, that's not a big commitment, 20 minutes a week. And we're comparing vigorous snacks to lower intensity snacks. So other movement breaks that are more stretching-based activities. Again, these are randomized controlled trials. And so right now we've just completed one study. We have another ongoing study in individuals who have type two diabetes. We're gonna embark on another one in people with overweight and obesity.

58:30
And so we hope to show with that work, we're moving it out of the laboratory. So it's fine to do these well-controlled laboratory-based studies, but when you try to move it a little bit more into real life, do people adhere? So these are feasibility trials. Will people actually do this when we deliver it in this manner? So that's one approach that we're looking at. We're also, we're very interested in this whole idea of exercise domains, critical power, but trying to apply that more

59:00
to exercise prescription away that that people are less familiar so what i mean by that is we traditionally benchmark intensity training using for example heart rate metrics we're looking at some of these other markers to see if we can reduce the variability in the response of this we have a hundred people do our studies some people have tremendous gains some people don't change much at all is there a way for us to try and.

59:25
optimize the delivery so that more people stand to benefit? We're always going to see individual differences, but can we try and optimize that a little bit more so more people we see beneficial responses? Yeah, and that no responder thing is super interesting. Is it just that the dose may not be correct for that individual rather than that they're never going to respond? Or do we even know? Yeah, so I think number one is I don't think there's any

59:51
non-responders to exercise. We can see non-response in certain parameters. So maybe your blood pressure doesn't change. Maybe your VO2 max doesn't change. But that doesn't mean that all of the beneficial effects that we see with exercise aren't going to change. So I think it's selective non-response to selective variables. And also probably what that means is you have to do something more. You have to do something different, right? And so...

01:00:18
There's some out there who would suggest there's no such thing as exercise non-response at all if you work harder or you do more of it, but even that's a bit of a debatable argument I think. Yeah. Oh, nice one, Martin. So I will put links in the show notes to the studies that we discussed and of course to your book, The One Minute Workout. And I feel that you gave a really good message of hope actually.

01:00:43
today for us non-recovered endurance athletes who really just want to go in that grey zone to the people who are really just sort of looking for those first steps. Martin, where can we find more about what your lab is doing? What's the easiest place? Yeah, so I do have a website martingabala.com where we try to post information on our work, podcast links to interviews like this. I really appreciate the opportunity.

01:01:10
I am on Twitter at Gabala M sparingly, but people can reach out to me there as well or the contacts are on the website as well. So I really enjoyed our conversation. Thanks very much for this opportunity, Nikki. Thanks so much, Matt, and really appreciate it.

01:01:38
Alrighty, hopefully you enjoyed that. It was so great to have a chat to him. And in fact, it was also awesome because I in fact met him in person about this time last year when we were both at the sports medicine conference in Kona. He of course was presenting his amazing research and I was doing what I always do and was sitting in and absorbing all of that. So I feel really honored that he came onto the podcast to share some of that with me and of course with all of you today.

01:02:06
Next week on the podcast I speak to Dr James Mueke all about eye health, type 2 diabetes and being an advocate for health in the Australian public health system. Until then though, come and leave me a comment and tell me what you think about this interview over on Instagram, threads or Twitter @mikkiwilliden.

01:02:29
Facebook @mikkiwillidenNutrition, head to my website, mikkiwilliden.com, and book a one-on-one call with me. All right, team, you have the best week. See you later.