The Misconceptions of HIIT (And the Role It Can Play in Your Fitness Routine)
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Summary
Dr. Martin Gabala is a foremost researcher of this fitness modality and the author of The One Minute Workout: Science Shows a Way to Get Fit That's Smarter, Faster, and Shorter. In this episode, Dr. Gabala explains the main, underappreciated advantage of HIIT, which revolves around the intensity-duration tradeoff: the higher intensity you make exercise, the shorter your workouts can be while still triggering improvements in metabolism, cardiovascular health, and mitochondrial capacity.
Transcript
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Brett McKay here, and welcome to another edition of the Art of Manliness podcast.
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You've probably heard of HIIT, high-intensity interval training.
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In fact, you may feel so familiar with the idea that you think you understand it, but
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People often hold some popular misconceptions about HIIT, and today we'll unpack what some
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of those are with Dr. Martin Gabala, a foremost researcher of this fitness modality and the
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Science shows a way to get fit that's smarter, faster, shorter.
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Martin explains the main, underappreciated advantage of HIIT, which revolves around the
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The higher intensity you make exercise, the shorter your workouts can be, while still triggering
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improvements in metabolism, cardiovascular health, and mitochondrial capacity.
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We get into the fact that the intensity of HIIT needn't be as high as you might think,
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and that, contrary to popular belief, sprinting at intervals is actually a predominantly aerobic
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Martin answers questions like whether zone 2 cardio has an advantage over HIIT, if the
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so-called afterburn effect of HIIT is real, if you can do HIIT if you're older or have heart
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problems, and whether you should worry about the way HIIT can raise cortisol in the body.
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He also shares specific HIIT workouts you can do, including a walking interval workout and
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one of the best higher-intensity protocols to try.
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After the show's over, check out our show notes at awim.is slash HIIT, and that's H-I-I-T.
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So you are a professor of kinesiology at McMaster University in Canada, and you spent a lot of
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your career researching high-intensity interval training, or HIIT.
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Yeah, sort of a personal and professional interest.
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The personal interest is when I first got to McMaster, I was a busy young assistant professor,
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had a working spouse, two young kids at the time, and so, you know, quite ironically for
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a professor of exercise physiology, I found myself with very little time to exercise, and
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For a long time, I've taught a fourth-year course called The Integrative Physiology of
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Human Performance, and my students are always interested in the training regimes of high-level
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And so I would ask them, you know, why do these elite endurance athletes sprint?
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Why do they run hard or do these short, intense workouts to enhance their aerobic performance?
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And so it was those combination of things that led me down this path.
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I think everyone at this point has probably heard of high-intensity interval training or
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I mean, this is about when your book came out, the one-minute workout came out, and you
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wrote some articles for the New York Times, like, went viral.
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Like, you could just do a short workout, really intense, and get all these benefits.
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But I think when most people think of HIIT, and I know I did this before I read your book,
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they typically think it's got to be a bootcamp style, super intense, crossfit, workout of
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But one of the points you make in the book is that idea of HIIT, well, that is HIIT.
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So how do you define high-intensity interval training?
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And for sure, this idea that you need to go all out or as hard as you can go, that's a big
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Certainly, that's one type of high-intensity interval training, but it's not the only type.
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And so to me, HIIT is very simply alternating bouts of relatively hard work and recovery
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Now, high-intensity, we can generally equate that with vigorous intensity effort, you know,
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And there's well-defined metrics in physical activity, exercise, prescription guidelines
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So if you could imagine a simple 10-point subjective scale where one is laying on the
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couch or complete sedentariness and 10 is sprint from danger pace or save your child from an
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oncoming car, vigorous exercise or HIIT is about a seven.
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It roughly corresponds to about 80% of maximal heart rate.
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And for an athlete, it means the severe intensity domain.
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And we use other metrics such as critical power, critical speed.
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But key point here is that it is not only all-out exercise.
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Absolute intensity can vary dramatically between individuals, but the relative intensity can
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What constitutes intensity is going to vary from person to person.
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So someone who's super fit, crossfitter type guy, what that person has to do to get to a high
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enough intensity to have a high-intensity interval training workout, it's going to be different
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from someone who hasn't worked out or exercised in 30 years.
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And their intensity might just be they get up off the couch and they walk briskly for a little bit.
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There's a figure I like to show in presentations to different stakeholders, and it's two heart rate
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tracings from two individuals on very far ends of the fitness spectrum.
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And the top heart rate tracing is from an Olympic athlete, and the bottom tracing is from an
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individual with coronary heart disease, but they're both doing the same interval training
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They're both doing four-minute intervals at about 90% of their maximal heart rate.
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Now, of course, the Olympic athlete is working at a very high pace.
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And as you alluded to, the deconditioned patient is hardly doing much more than a walk or a brisk
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walk, but it really is a dramatic illustration of this notion that we can really scale absolute
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intensity to elicit the same relative stimulus, even if people are on very far ends of the
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So another important part of HIIT is the interval part.
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So it's not just you're going hard for as long as you can.
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The idea is that you take a break from it every now and then and then go back up.
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So you're trying to create just this wave of extremes in your workout.
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We talk about hills and valleys and, you know, going back to athletes, you know, a common
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refrain is make your hard days hard and your easy days easy.
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And those recovery periods are very, very important in order that you can go hard in the subsequent
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But this ungenerating pattern is intrinsic to the method.
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So basically HIIT is alternating higher intensity bouts of exercise with lower intensity in the
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And you're alternating because you can't stay very high intensity for long.
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I mean, the idea is, and we're going to talk about this more as we go along, but by ramping
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up the intensity, just a few short bouts of exercise can give you a lot of the benefits,
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just like longer sessions of exercise, but in a shorter amount of time.
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There's an old saying that your heart doesn't know what your muscles are doing.
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It just, you know, realizes it's some sort of physiological stress or challenge.
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And what we're finding is that, you know, intensity really plays a key.
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And so we can definitely trigger responses through traditional moderate intensity, continuous
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But many of those hallmark adaptations, it seems we can trigger with a surprisingly small
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So while HIIT really burst on the scene, I'd say, you know, the middle of the 2000s, early
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2010s, one thing you do in your book is that you highlight that athletes and other professions
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like the military as well, they were using HIIT without even knowing they were using HIIT
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So athletes tended to perform high volume, high intensity interval training.
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And so there's very famous examples of people like Paavo Nermi, Emil Zadopek.
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These are Olympic champions in multiple events.
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And for example, legend had it that Zadopek sometimes completed 15 miles a day of intervals
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But also there were individuals like Roger Bannister, who famously trained with intervals on his
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lunch hour when he was a very busy medical student running repeats on a quarter mile track.
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And then you also highlight, I thought it was interesting, the Canadian, this is the Air
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Force or it was one of the military units in Canada.
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They, this guy stumbled upon HIIT and he used it to help get new recruits in shape.
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One of the first exercise physiologists was hired by the Canadian military at sort of the
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Because at one time you can imagine these service members stationed in very remote outposts, you
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And at one time, so many Air Force pilots were unfit, about a third were deemed unfit to fly
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And so the government realized they had to do something about it.
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But, you know, you're stationed in the far North, not a lot of specialized equipment.
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And so they came up with this plan called 5BX, which stood for five basic exercises.
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And sort of the tagline was you could get fit with these simple bodyweight style exercises.
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It only took about 11 minutes a day and this spread well beyond the military.
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And eventually about 20 million of these pamphlets were distributed to Canadian households in
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There was an equivalent plan for women called XBX.
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But again, it was this idea that you could get fit, didn't have to be fancy, didn't require
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a lot of time, but it was based on this idea of, you know, getting up to a vigorous pace in
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Well, we've been talking about you can use HIIT to get fit, I mean, increase fitness.
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And in the book, you talk about there's, you know, we have different systems in our body,
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How does HIIT make us more fit, both anaerobically and aerobically?
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And I guess we'd have to explain what the anaerobic systems are and the aerobic systems
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So basically two ways of generating energy within the body.
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So you can imagine we literally are burning fuels such as sugars and fats using molecular
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And so very much like a fire, you know, you need wood for the fire.
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You need oxygen and you need the spark as well to keep the fire going.
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Now, we can also produce some energy without the use of oxygen.
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And so this is the notion of anaerobic or non-oxidative energy.
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And you could think of a spectrum or a continuum rather, where the aerobic system is great in
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terms of capacity, very high overall amounts of energy, but it comes at a cost of it's slower.
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And so non-oxidative or anaerobic energy, it doesn't require oxygen.
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It's very, very fast in terms of the rate at which it produces energy, but its capacity
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And so for a long time, it was thought, or you still hear this very commonly today, that
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Any type of repeated sprint is primarily fueled by the aerobic or oxidative energy supply system.
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And so, you know, you can think of team sports or that, but repeated sprints very much an
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And so it's not surprising then that we see these profound responses within the aerobic
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You know, even during a 30 second, as hard as you can go, all out sprint, about 20% of
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And then when you do repeated 30 second all out sprints, the predominant energy providing
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Yeah, that's really interesting because, yeah, I've heard that same thing that sprinting
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And if you wanted to get aerobic conditioning, you have to do the more steady state cardio.
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You know, like why does that idea still exist that sprinting only engages the anaerobic system
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when sprinting at intervals, at least, you're actually engaging the aerobic system too?
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Yeah, well, there's no doubt, you know, if you want to become a better sprinter, you better
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And so sprint training, it will definitely stimulate non-oxidative energy metabolism and
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again, literally make you a better sprinter and develop those enzymes in that supply method.
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It's a fact that when you do a single sprint, most of the energy is anaerobic.
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But again, it's very, very different when we do these repeated sprints.
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And so I'm not really sure why that endures so much or we use these terms like aerobic and
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anaerobic and, you know, another misconception is that we only utilize one system or the other.
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We're very much, you know, virtually every type of exercise that we do, whether it lasts
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a few seconds or many, many hours, there's always going to be some blend or some contribution
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But again, suffice to say, repeated sprints, very potent aerobic stimulus.
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And, you know, that's associated with a wide array of health benefits as well when we develop
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So what are the aerobic responses our body has when we take part in repetitive sprinting
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Yeah, probably the biggest one is cardiorespiratory fitness.
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And, you know, that's that notion of cardio health.
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It's largely determined by the capacity of your heart, your blood vessels to circulate oxygen
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We measure that clinically or in a laboratory with a maximal oxygen uptake test.
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That's clearly very important for athletes, but there's very strong and compelling epidemiological
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evidence to show that having a higher cardiorespiratory fitness is associated with a lower risk of dying
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from all causes, a lower risk of developing many different chronic conditions like cardiovascular
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And so any way that we can enhance our cardiorespiratory fitness is really, really important.
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So you can sort of think of your cardiorespiratory fitness as the ceiling, right?
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And we want our ceiling to be as high as possible.
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And then the other aspect to fitness is metabolic fitness.
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And that sort of regulates how close to the ceiling you can work for a prolonged period of
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And so, you know, athletes want high cardiorespiratory fitness and a high metabolic fitness.
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They want a big ceiling and they want to be able to work close to that for a long time.
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But it's again, the underlying physiology is the same.
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And so individuals who are very deconditioned, they often have low ceilings, but they have
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a very low percentage of the ceiling that they can work at as well.
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And so any type of exercise training will tend to enhance both of those things.
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But again, we've learned that the vigorous intensity intermittent exercise can be, you
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What that really means is there's some time efficiency there and we can get away with less
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total time and probably exercise and still get to a similar level of improvement.
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Yeah, so you could do an hour of steady state cardio and get, you know, X amount of benefits
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in terms of VO2 max or increase in mitochondria in your cells, or you could do a 10 minute high
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intensity interval training and get roughly the same benefits.
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And, you know, you very much see these arguments where people will try to demonize traditional
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cardio or now there's sort of a pushback against HIIT.
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You know, I really have a ton of time for those.
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Again, I think at least from our research, what we've been trying to do, we talk about
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expanding the movement menu, which really means, you know, we've largely been telling people
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to do the same thing for a long time and that's fine.
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The physical activity guidelines are based on excellent science, but we know a lot of people
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And one of the perceived barriers, whether it's real or not, is a perceived lack of time or
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people think, oh, if I don't have an hour in the day, I'm going to blow off my
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And I think what the interval training literature is showing is, you know what, you don't need
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a whole lot of time and still get some bang for your buck there.
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And really that's been our, the focus or a focus or through line of our research is,
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you know, trying to establish the scientific credibility of these brief, vigorous type
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And then, you know, hopefully presenting that as an option to people.
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We're not saying it's the only work that you should do or, you know, if you don't like
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Go do the moderate stuff, but trying to expand that movement menu, give people more physical
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Just like we try to give options for dietary strategies, you know, pick the food you like.
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You can sort of pick the exercise approaches that you like because the best one is what
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You're more likely to stick with it over the longterm.
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It seems like people keep rediscovering HIIT or interval training, you know, every 10 years
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You'll see these trends where like, oh, it's steady state cardio.
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Because I think in the past five years, I've seen a lot of talk about zone two cardio where
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it's, you know, you want to stay in zone two for 60 minutes and get so much of it a
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It allows me to watch movies and television shows that I don't otherwise wouldn't watch.
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But I think what your research is showing is that there's nothing wrong with zone
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But if you don't have time, HIIT might be an option for you.
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And so, you know, I think some of the, and you're right, you know, these things come in
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and out of fashion a little bit, but I think some of the pushback against HIIT comes certainly
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from some overstatement regarding potential benefits of HIIT, you know, hopefully not from
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our laboratory or interviews like this, but definitely, you know, see, you see some overstatement.
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You can get away with a few minutes a week and, you know, that's the solution for
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fitness or, so when we start saying, you know, this is the solution to our inactivity
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problem, or this is the best way to exercise or the optimal approach, I, I think that's
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You know, to my mind, the rise of zone two is owing in part to, that's how high level
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endurance athletes train in terms of a roughly an 80-20 split.
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So if you're a high level endurance athlete, you know, training 25, 30 hours a week, there's
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very good evidence to show that they tend to center around this 80% low intensity, 20%
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And so, you know, it's interesting because classically zone two has meant the heavy intensity
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domain, and this is where there's a classic three zone training model for, for athletes.
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But, you know, now zone two has commonly been interpreted as low intensity, sublactate
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And you're right, you know, it's, it's definitely can be beneficial.
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You know, I'm, I'm unconvinced or I just don't see the data that zone two is best to optimize
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And so I think, again, ideally we should train across a range of intensities, but I'd come
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back to this idea that I think as, as volume decreases, intensity is arguably more important.
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And so where I would take some exception to the commentators is suggesting that because
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athletes who do 25 hours a week train this way, that's how everyone else should exercise,
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you know, regular people who might have an hour a week or, you know, two hours a week
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to exercise, or maybe they only have 20 minutes that they're willing to do.
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I think they're doing anything is clearly better than nothing, but engaging in a more vigorous
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It's better bang for your buck, certainly given the time investment.
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I know I made a big emphasis on zone two starting two years ago because the, the, the sales pitch
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on, oh, it helped increase the amount of mitochondria in your cells.
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I was like, well, that sounds like it's important.
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And so I'm doing two to three hours a week on the elliptical watching Cobra Kai on YouTube,
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but I'd have days where I couldn't get a session in a zone two sessions.
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It's like, well, I'm not going to get that mitochondria that I need.
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But then after I read your book, this happened to me last week.
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So I just got on my airdyne bike, the fan bike, and I did a interval thing.
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And I got some, I got some of those aerobic benefits from doing that 10 minute interval
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And that's the key takeaway, I think is lots of different options, even for a given individual,
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you know, I'm, I'm a committed exerciser to this approach.
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Well, if I can't do my approach on that day, maybe I'm going to try something different.
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And, you know, to your point, when time is pressed, maybe engage in some of the vigorous
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And even, even if only you do it for five or 10 minutes, know that you're still getting
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some benefit there, at least to maintain your fitness, you know, until you can get back
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So hit, you can get the same aerobic benefits as doing the long and slow and steady cardio.
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I mean, you talk about how it can improve our cardiovascular health, reduce, you know, our
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I mean, you also at how hit can help improve or manage diabetes and insulin resistance.
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And so again, I want to be, you know, I want to really emphasize here, any type of exercise
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And so these are not necessarily exclusive benefits to hit, but certainly some evidence from our laboratory,
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a lot of other laboratories shows that hit can improve measures of insulin sensitivity
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And so part of the reason for that is that, you know, we have in our body, these things
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They're in all of our tissues, but they're responsible for sort of moving the glucose molecules
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or the sugar out of the bloodstream into our cells, or it can be taken up and stored or
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And so exercise generally, and in particular vigorous exercise, enhances the capacity for
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And so that's likely one of the reasons that blood sugar control can be managed a little
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Or certainly if you're an individual with type 2 diabetes and you engage in regular exercise,
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one of the things that you'll find is your physician is going to say, well, you need less
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of your medication because the exercise is doing that for you.
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And so we don't now need to give you drugs or as many drugs in order to try and regulate
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your blood sugar because you're sort of doing it on your own through physical activity.
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Another benefit I've seen touted for HIIT is weight loss, this idea of the afterburner
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Again, it's one of these things I think that's often overstated.
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And so, you know, you look online and you might see someone's comparing an interval versus a
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traditional cardio workout and see this massive afterburn effect.
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So this idea of a heightened metabolic rate in recovery, you have this transiently higher
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So people say, you know, how can HIIT, especially if it's short, result in any calorie burning
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Well, it does relate to this idea of the afterburn effect.
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But again, it's relatively small and we shouldn't overstate it.
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And, you know, HIIT can play a role in weight management efforts, just like other types of exercise.
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But, you know, the nutrition side of the equation is the primary driver there.
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We're going to take a quick break for your word from our sponsors.
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Okay, so HIIT can improve our aerobic capacity.
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It can improve our cardiovascular health, can help with insulin sensitivity, with weight
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How much HIIT do you have to do to get these benefits?
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And like how many sessions do you have to do before you start seeing these benefits?
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And so definitely the responses, the adaptations, they can occur surprisingly quickly.
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So we're talking within a week or two, you know, we've done a study, for example, in
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older overweight individuals with type 2 diabetes, and we put them on a HIIT protocol that was
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And even after two weeks, we saw marked improvements in some of those things that I was talking about,
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their glucose transport capacity, some markers of blood sugar control.
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And probably the more deconditioned you are, the faster the response is, you know, you probably
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We've got to be careful there because, you know, we're not saying to these people that,
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especially if you're very deconditioned, HIIT does not mean jumping off the couch and pedaling
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It's just, you know, getting out of your comfort zone, going a little harder than you may have
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So it definitely can occur quickly in terms of how long the sessions have to be.
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Again, this is where it really comes back to what's the intensity.
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And so there's many different HIIT protocols, but certainly 10 minute total time commitment
00:25:10.620
involving, you know, one to two minutes of vigorous intensity exercise can be enough if you do that
00:25:17.280
over a few weeks to start to see measurable improvements in various health and fitness markers.
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And just to recap, the intensity we're going for is on a scale of one to 10.
00:25:33.500
And obviously, you know, and for reference there, a traditional moderate intensity would
00:25:37.240
be about a five on that range to help people try and scale it.
00:25:40.880
How do people typically feel when they're at a seven?
00:25:42.900
It's like you're breathing really heavy, you're sweating.
00:25:44.980
Like what are some of the physiological responses?
00:25:47.440
And so one of the classic ones is, you know, moderate exercise being that five, you could
00:25:51.340
carry on a conversation or you could talk in sentences, but you wouldn't want to sing.
00:25:55.860
Whereas if you're into that vigorous range, you know, you can grunt out a few words, but
00:26:00.120
you really don't want to speak in sentences or have a conversation.
00:26:03.220
So there's sort of, that's what we're talking about there in terms of these subjective cues
00:26:11.120
The interesting thing is, especially with the short of the intervals, some of these traditional
00:26:15.380
metrics, whether it's heart rate or relative to VO2 max or heart rate reserve, they, they
00:26:23.480
And so, you know, if we're talking 20, 30 second efforts, people can go at a surprisingly
00:26:29.080
high pace, but they don't perceive it as such because the, the effort is over quite quickly.
00:26:36.180
And so it's, it's a real challenge, frankly, in terms of trying to apply some of these brief,
00:26:41.840
vigorous protocols widely and try to translate this into exercise prescription for people,
00:26:47.940
because a lot of the metrics that we normally use don't necessarily apply.
00:26:52.660
But, you know, this idea of perceived exertion, that zero to 10 scale, it's probably about
00:26:57.060
the best we have in terms of applying this widely and in a way that people can understand.
00:27:01.920
And then what your research has shown, the higher you go up in intensity, the shorter
00:27:08.840
You know, there's clearly an intensity duration trade-off.
00:27:15.120
So as the intensity really gets up there, the dose that you need, the volume or the time
00:27:24.240
And there's, you know, some very clear research to, to show that.
00:27:28.320
Does HIIT affect men and women any differently or is it the same?
00:27:33.320
So I, there's definitely some differences related to biological sex, but they appear
00:27:41.600
There's a much greater range or scale for just fundamental inter-individual differences
00:27:50.300
But some of our work, some research from others has shown, you know, subtle differences.
00:27:56.420
And, you know, you can point to some underlying biological variables there, maybe related to hormone
00:28:01.540
concentration or the estrogens that could potentially impact on this from a mechanistic basis.
00:28:07.060
But again, suffice to say a little bit of evidence, maybe females don't have as pronounced
00:28:15.580
But again, I think that's more related to just inter-individual differences between humans
00:28:23.440
And clearly both men and women can benefit from interval training and benefit from, you
00:28:31.040
There might be some older men listening to this podcast.
00:28:33.700
Maybe they're in their 60s and 70s and they're like, oh, I don't want to do that HIIT because
00:28:42.220
So I like, you know, and to that specific example, no one has to do HIIT if they don't
00:28:50.080
Now, number one is if we look at the physical activity guidelines that generally recommend
00:28:53.960
moderate to vigorous exercise in prescribed amounts, the suggestions or the recommendations
00:29:00.900
are essentially the same for adults 18 to 64 and older adults 65 plus.
00:29:07.120
Now, that's not saying that if you're 65 plus, you should explicitly do vigorous exercise
00:29:14.800
But again, when we look at the guidelines, adults of all ages are recommended to do vigorous
00:29:21.960
I think we clearly need to be mindful of chronic conditions, both musculoskeletal and as people
00:29:28.800
age, there tends to be increased potential silent risk factors, cardiovascular disease risk
00:29:35.600
And so, you know, the standard advice, of course, is that people should see their doctor if they're
00:29:45.260
So if you're just getting into exercise, physical activity, start with the moderate stuff, then
00:29:50.920
But also, people do not necessarily need to be afraid of vigorous exercise and more people
00:29:57.940
than we think, many more people than we think can perform vigorous intensity exercise HIIT
00:30:04.980
And I think there's fairly compelling data in that regard.
00:30:07.520
And definitely HIIT has been applied to individuals with many different chronic conditions, including
00:30:12.840
cardiovascular disease, metabolic syndrome, older individuals, people with cancer.
00:30:17.900
So again, my take-home points, there are many more people than we think can do vigorous
00:30:23.400
exercise, but of course, people need to be smart, ideally get checked out.
00:30:28.040
And the older you get, you know, maybe back off on the sprint and all out stuff unless it's
00:30:36.560
And you also point out, which is interesting, in the past 20, 30 years, cardiologists or heart
00:30:42.060
hospitals, at first they were very leery of HIIT because they're treating people who had
00:30:46.920
cardiac events, heart attacks, like, well, that's just going to hurt them even more.
00:30:50.820
We don't want to do that because it's so stressful in the heart.
00:30:52.860
But you're starting to see a lot of them incorporate that in the recovery process of heart attack
00:30:58.140
They're not going to do the all-out 10 sprint, but they're getting their patients to do vigorous
00:31:06.640
Because what the studies have found is that it helps strengthen these people's hearts that
00:31:14.240
You know, and at one time, you know, rest was all that was prescribed after a heart attack.
00:31:18.360
And at one time, you know, we wouldn't think that anyone who was a post-MI patient would
00:31:24.460
And now we know that many cardiac rehab programs incorporate resistance training.
00:31:29.080
And so I think it's the same with vigorous exercise.
00:31:34.220
But, you know, and it depends across the world.
00:31:38.540
But, you know, for example, in Scandinavia, I think interval training is much more an accepted
00:31:46.360
We're a little bit less, I would say, in North America.
00:31:51.760
But clearly, vigorous intensity exercise HIIT is being utilized widely in cardiac rehab.
00:31:58.880
Does HIIT raise your cortisol more than other forms of exercise?
00:32:03.960
You know, I'm less concerned or I'm not convinced sort of these acute fluctuations in hormones
00:32:13.780
And I don't think there's evidence that, for example, you have sustained rises in cortisol
00:32:18.500
or other hormones that, you know, might be associated with muscle breakdown or stress.
00:32:24.740
So I don't think it's something that people need to be concerned about.
00:32:28.040
So since your research has started, you've had other researchers in other fields look
00:32:34.520
at HIIT, and you've had exercise psychologists look at HIIT.
00:32:38.200
And one thing that some of these exercise psychologists are finding that HIIT is a really
00:32:43.060
effective way to get novice exercisers to start the exercise habit, which seems kind
00:32:49.920
of counterintuitive because HIIT can be really unpleasant.
00:32:53.400
And unpleasantness is one reason why people don't stick with an exercise plan.
00:32:59.120
So have they figured out why is HIIT such an effective way to get beginning deconditioned
00:33:08.360
Yeah, this is a real hornet's nest, I would say.
00:33:10.600
And among the exercise psychology community, you know, and I'm not a behavioral expert, there
00:33:15.640
are really polarizing opinions around the potential for HIIT as a public health strategy.
00:33:21.720
And you're absolutely right, one camp would say, you know, if exercise is vigorous, if
00:33:27.880
it's intense, people find it unpleasant, and so they're unlikely to do it.
00:33:33.540
And so, you know, HIIT is bound to be a public health failure.
00:33:39.340
And there's definitely a lot of exercise psychology, behavioral research coming out to suggest that,
00:33:45.200
you know, okay, wait a minute, brief, vigorous, intermittent exercise.
00:33:49.140
It's completely different from continuous, vigorous exercise.
00:33:53.900
It also depends when are you asking people the question.
00:33:57.300
You know, if you ask them during the bout, they might rate hit a little bit lower.
00:34:00.700
But after the bout, they're like, you know what, didn't take me as long.
00:34:06.300
And there was a recent meta-analysis based on over 100 studies, almost 9,000 participants
00:34:12.820
that found similar rates of measures like compliance and adherence to high-intensity interval training
00:34:20.660
and moderate-intensity continuous training, so such that those were not different.
00:34:25.060
So I think, you know, you can cherry-pick individual studies.
00:34:29.280
And for the critics of HIIT, I would say, well, you know, what's the fallback?
00:34:32.820
Because we know that the adherence to the broad public health adherence to moderate exercises
00:34:40.140
And so to demonize any form of physical activity doesn't make sense to me if arguably we're all
00:34:47.900
And we agree that the biggest thing that we need to do is just get more people active
00:34:55.560
You know, again, coming back to this idea, the more exercise options, the better.
00:34:59.220
Let's expand that movement menu rather than sort of demonize one particular approach.
00:35:03.400
I think one point a psychologist made was that when you take a deconditioned person, someone
00:35:08.020
who hasn't exercised, and then put them on the path to run a 5K, when they're first starting,
00:35:14.220
they're doing interval training, but unintentionally, because they can only like run maybe a few
00:35:19.580
hundred feet, then they got to stop and walk, and then they catch the bread and they start
00:35:22.720
like, they might in the person's head, they think they're doing steady state cardio, and
00:35:26.900
they think they're failing because they're not running the entire time.
00:35:30.140
It's like, no, actually, you're just doing interval training.
00:35:32.780
You're getting all these great health benefits doing that.
00:35:36.960
You know, it's sort of like changing the narrative or flipping it on its head, and it can be a very
00:35:43.720
You're not a failure because you can't sustain a pace for 30 minutes.
00:35:49.680
They sort of go hard, they take a break, and they do it again.
00:35:54.900
And so, I think if you're looking for buy-in or that, rather than telling someone they're
00:35:57.980
a failure because they can't do 20, 30 minutes continuous because their starting capacity
00:36:02.340
is so low, saying, hey, an intermittent approach works just fine.
00:36:08.000
Okay, so the HIIT workout, you're not saying it's better than or steady state cardio.
00:36:12.920
It's another option to choose from in your fitness repertoire.
00:36:17.780
So, if you don't have time for an hour-long zone two cardio session, just do a 10-minute
00:36:25.120
interval workout, and you get all these benefits in terms of aerobic metabolism, cardiovascular
00:36:29.200
health, insulin, diabetes, weight loss, you get all those benefits with just maybe 10
00:36:40.520
It's not necessarily the best or for everybody, but definitely work it into your fitness menu.
00:36:46.120
All right, well, let's talk about some HIIT workouts that people can do.
00:36:48.860
So, after listening to this episode, they'll do some or have that as an option.
00:36:52.340
What are the type of movements you can do for HIIT?
00:36:55.940
So, again, getting back to this idea of your heart doesn't know what your muscles are doing,
00:37:00.220
again, generally speaking, I don't think it matters.
00:37:02.780
And our research would suggest it wouldn't matter if it's indoor-based cycling, if it's
00:37:07.640
stair-climbing exercise, if it's uphill, if it's bodyweight-style exercise.
00:37:12.720
All of those things can be utilized effectively as an interval training workout to stimulate
00:37:18.320
improvements in all of those metrics that we were talking about there.
00:37:21.860
So, I don't think, and again, we're talking general health improvement here.
00:37:26.760
You know, if you're an athlete, you try to train very sports specifically.
00:37:30.560
And so, if you're a cyclist, you better train with interval cycling to try and get better.
00:37:35.280
But, you know, for most people, that's not the key driver.
00:37:38.160
They just want to enhance their cardiorespiratory fitness and other health metrics.
00:37:42.040
And so, probably varying it up is a good strategy.
00:37:45.900
But the specific type of movement doesn't matter so much.
00:37:49.900
Just whatever you like, whatever you enjoy doing.
00:37:52.980
So, what's a good interval workout for, I get to say, a rank beginner?
00:37:58.920
One is, you know, probably you want to get out of your comfort zone.
00:38:02.600
But again, you're not doing this all out 9 or 10 on a 10-point scale exercise.
00:38:07.420
And so, you know, if your standard exercise is walking around the block or continuous moderate
00:38:13.220
exercise at about a 5 there, you know, getting out of your comfort zone.
00:38:17.320
Start with a 6, maybe get into a 7, and, you know, do that for a minute or so and then
00:38:23.500
But classic examples would be, you know, 3 minutes on, 3 minutes off.
00:38:27.560
And there's a ton of research, much of it out of Japan, that has looked at this interval
00:38:33.300
walking as a strategy and just showing the tremendous benefits that that can elicit.
00:38:40.880
Another classic protocol largely developed in Norway is the 4x4.
00:38:45.220
So, that's four 4-minute efforts that are relatively high in intensity.
00:38:53.160
And what tends to happen is the intensity goes up and the duration of the intervals goes
00:38:59.480
So, we've looked at, you know, a 10x1 protocol.
00:39:02.260
And so, you know, how hard you're working there for a minute is harder than the 4-minute
00:39:07.060
But again, you're only doing a minute, not four of it, right?
00:39:10.000
And you repeat that in a sort of on-off pattern.
00:39:12.700
And I think that's also one of the beauties of interval training is the infinite variety.
00:39:17.080
People say, what's the best interval training protocol?
00:39:21.080
Again, generally speaking, unless you're an athlete training for a very specific performance
00:39:29.760
And hopefully, you know, it takes away the boredom a little bit because, you know, vary
00:39:34.160
There's only so many ways to get on a treadmill and jog at a moderate pace for an hour or so.
00:39:40.620
Intensity, duration of both work, recovery periods, all of that.
00:39:45.080
That Japanese protocol, is that the Tabata protocol?
00:39:48.240
No, it would sort of be one over the Tabata protocol.
00:39:51.740
So, there has been some classic interval training work out of Japan almost at the ends of the
00:39:56.340
So, that three minutes on, three minutes off, that's just very much brisk or interval walking.
00:40:01.680
Whereas, Professor Izumi Tabata is, you know, the father of Tabata intervals, that's at
00:40:09.260
And that's, you know, 20 seconds at a 10 out of 10 pace, right?
00:40:13.240
As hard as you can go, 10-second recovery, and then you do it again eight times.
00:40:18.000
So, you know, a Tabata workout classically lasts four minutes.
00:40:22.280
20 seconds on, 10 seconds off, repeated eight times.
00:40:25.340
But a Tabata workout is one of the most challenging interval protocols that you can do.
00:40:30.540
So, yeah, the key takeaway there is the more intense you go, the shorter your workout can
00:40:36.260
But the less intense, if you're doing just a walk, your intervals will have to be longer.
00:40:44.000
You know, at the end of the day, there's no free lunch, right?
00:40:45.860
And so, if you definitely want the benefits of brief exercise, it needs to be intense.
00:40:54.000
And at the other end of the spectrum, you can still do interval training.
00:40:56.940
It doesn't have to be this all out as hard as you can go.
00:41:00.420
But, you know, you're invested then for a couple of minutes and repeating that at least,
00:41:06.480
One you highlight that I like is the Wingate Classic.
00:41:12.900
So, the Wingate is sort of a classic test in exercise physiology.
00:41:16.460
It's also known as the Wingate Anaerobic Test, going back to our earlier discussion.
00:41:21.060
And that's because it's 30 seconds as hard as you can go.
00:41:25.560
And it's actually performed on a specialized bike or a specialized ergometer that sort of
00:41:33.200
And so, you know, even as you're fatiguing, you're still having to go.
00:41:37.780
It's about the longest 30 seconds of your life.
00:41:40.540
And so, our initial work was utilizing a Wingate protocol as sort of the extreme, right?
00:41:46.640
It was a proof, you know, proof of concept studies at the time.
00:41:49.380
And so, people would do these protocols where it took, you know, four, five, six of those
00:42:00.500
And, you know, it's almost a variation on a Tabata workout.
00:42:03.940
And then over time, we've sort of dropped the overall time, dropped the overall intensity,
00:42:10.640
You have the, it's the 10 by 1 is your variation of the Wingate.
00:42:15.160
And again, you know, all different protocols appeal to different people.
00:42:18.200
But probably if I had to pick one that seems to be widely suited or widely rated as not bad,
00:42:24.760
it's this 10 by 1 protocol, you know, almost seemingly hits that sweet spot between it.
00:42:30.060
You know, the intervals are not too long, but they're not too hard either.
00:42:35.760
And then more recent research by others has shown that, you know, 5 by 1 can be almost
00:42:42.660
And so, it's a bit like, you know, bench press exercise.
00:42:45.380
You know, three sets of bench are going to be better than one set, but, you know, maybe
00:42:51.000
You know, so if you do one set of heavy bench, you might improve your strength by 25 or 30%.
00:42:55.160
If you do three sets, maybe you're going to do 35 or 40%.
00:42:58.340
But again, if your time pressed, that one set might be enough.
00:43:02.360
And so, you know, maybe a few intervals are giving you 80, 90% of the benefit that, you
00:43:07.520
know, a much larger dose of intervals might do.
00:43:10.000
So yeah, the 10 by 1, just for listeners, your first sprint is at an intensity of 5.
00:43:18.780
Then your second sprint is going to be at a slightly higher intensity level.
00:43:24.940
And then you just keep that cycle going until you get to an intensity level of 9.
00:43:30.900
And so, you know, one of the reasons we came up with that is because, you know, for a lot
00:43:34.560
of people, they're not outside trying to, you know, tailor their specific, you know,
00:43:40.560
You can imagine if you're exercising on a machine or you jump on a stationary bike, it allows
00:43:45.820
you to set a workload and just leave it there, right?
00:43:51.840
If it's a 20 point scale and you dial it up to a 12, the first minute at 12 only feels
00:43:59.700
But of course, as you start to fatigue over the course of the workout, you're still at
00:44:04.060
a 12, but the relative effort starts to creep up.
00:44:07.480
And so, again, it's a way to make it sort of simple.
00:44:10.300
I'm going to just keep it at a 12, but it's going to feel harder and harder each time as
00:44:18.940
I'm sure the publisher, your editor is like, we got to call this The One Minute Workout because
00:44:24.020
But is there a workout that lasts about a minute that can give you all these health
00:44:33.140
The One Minute Workout, sort of a tongue in cheek, but it was based on some of these micro
00:44:37.940
workouts where we're having people do three 20 second hard efforts.
00:44:43.820
Now, you know, the workout took about 10 minutes start to finish, but the hard stuff was only
00:44:48.000
a minute, three 20 second efforts interspaced with a lot of recovery in between.
00:44:53.760
Why I say a minute could be good is now we're starting to look at what we call exercise snacks.
00:45:00.500
And so how we define an exercise snack is a vigorous bout of exercise that lasts for a
00:45:08.400
And you do these periodically throughout the day.
00:45:11.200
So you can imagine on your way to work in the morning, you do a one minute vigorous effort.
00:45:15.840
Maybe you come into work, you take the stairs rather than the elevator as you're leaving at
00:45:22.220
You know, you exercise at a vigorous pace to get to the subway rather than a pedestrian pace.
00:45:31.760
And definitely in small laboratory based studies, if people do that a few times a week for a couple
00:45:37.260
of weeks, we can see measurable improvements in their cardiospiratory fitness.
00:45:41.400
That work, this small scale lab work is, is complimented by some other work that I've been
00:45:47.240
involved with led out of the University of Sydney, where the terminology, and again, you alluded
00:45:53.200
There's, you know, law, it's almost an alphabet soup when we start talking about this, but
00:45:57.240
the notion is vigorous, intermittent lifestyle, physical activity or VILPA.
00:46:04.460
But if we break that down, so vigorous is the effort that you require.
00:46:07.440
And hopefully your listeners have a good idea of what vigorous is by now, intermittent.
00:46:12.040
So it's periodic spread throughout the day and it's lifestyle, physical activity.
00:46:16.880
This is not structured exercise that you build into your calendar.
00:46:20.440
This is as you're going about your day, you know, you're, you're leaving work, you got
00:46:25.500
You can get there at a vigorous pace or at a pedestrian pace.
00:46:28.980
You know, you get off a long flight, you have the choice of the escalator or you can, you
00:46:33.760
know, grab your built-in workout gear, your suitcase, and you can walk up the stairs.
00:46:39.060
That would be an example of VILPA carrying a heavy backpack as you're doing your shopping
00:46:43.300
and research again, that I was involved with in a very large sample, over 25,000 individuals
00:46:50.860
who had worn accelerometers showed that as little as three to four minutes of accumulated VILPA
00:46:59.720
per day was associated with marked reductions in all cause mortality.
00:47:05.280
We're talking 30% reductions as compared to people who engaged in no vigorous intensity
00:47:14.060
And the risk reduction was even greater for cardiovascular disease.
00:47:17.820
So I think compelling, not cause and effect evidence, but compelling epidemiological evidence
00:47:23.760
that small amounts of vigorous physical activity can really move the needle in terms of enhancing
00:47:32.100
And so, you know, I've just talked about there about larger epidemiological evidence, small
00:47:37.580
laboratory-based studies, and where our research is moving now is sort of trying to round out
00:47:43.160
Larger, longer, randomized controlled trials where we're trying to look at this type of lifestyle
00:47:49.760
intervention and see, you know, how does it work when we try and use a best practice
00:47:54.820
design with control groups and things like that?
00:48:01.560
A few minutes of vigorous effort a day really, really pays benefits and it feeds into the
00:48:08.440
Well, Martin, this has been a great conversation.
00:48:10.260
Is there some place people can go to learn more about the book and your work?
00:48:13.960
So I do have a website, martingabala.com and sort of that's a one-stop shop for, you know,
00:48:21.820
People learn about a free online course that some colleagues and I at McMaster offer.
00:48:26.280
I'm not on X a lot, but you can find me at gabala.m.
00:48:36.360
He's the author of the book, The One Minute Workout.
00:48:40.440
Check out his website at martingabala.com where you can find more information about his
00:48:44.100
Also check out our show notes at aom.is slash hit and that's spelled H-I-I-T.
00:48:48.520
You'll find links to resources, including links to more details about how to do some of those
00:48:52.560
specific hit protocols we talked about towards the end of the show.
00:48:56.280
Well, that wraps up another edition of the AOM podcast.
00:49:05.460
Make sure to check out our website at artofmanliness.com where you can find our podcast archives as
00:49:09.480
well as thousands of articles that we've written over the years about pretty much anything you
00:49:13.680
And if you haven't done so already, I'd appreciate it if you take one minute to give us a
00:49:20.660
Please consider sharing the show with a friend or family member.
00:49:24.280
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00:49:26.840
Until next time, I'm Brett McKay reminding you to listen to AOM podcast, but put what you've