The Art of Manliness - The Misconceptions of HIIT (And the Role It Can Play in Your Fitness Routine)

00:00:00.000 Brett McKay here, and welcome to another edition of the Art of Manliness podcast.

00:00:11.500 You've probably heard of HIIT, high-intensity interval training.

00:00:15.440 In fact, you may feel so familiar with the idea that you think you understand it, but

00:00:19.860 do you?

00:00:20.900 People often hold some popular misconceptions about HIIT, and today we'll unpack what some

00:00:25.100 of those are with Dr. Martin Gabala, a foremost researcher of this fitness modality and the

00:00:29.500 author of The One-Minute Workout.

00:00:31.520 Science shows a way to get fit that's smarter, faster, shorter.

00:00:35.660 Martin explains the main, underappreciated advantage of HIIT, which revolves around the

00:00:39.580 intensity-duration trade-off.

00:00:41.440 The higher intensity you make exercise, the shorter your workouts can be, while still triggering

00:00:46.000 improvements in metabolism, cardiovascular health, and mitochondrial capacity.

00:00:50.720 We get into the fact that the intensity of HIIT needn't be as high as you might think,

00:00:54.440 and that, contrary to popular belief, sprinting at intervals is actually a predominantly aerobic

00:00:59.800 rather than anaerobic workout.

00:01:02.060 Martin answers questions like whether zone 2 cardio has an advantage over HIIT, if the

00:01:06.040 so-called afterburn effect of HIIT is real, if you can do HIIT if you're older or have heart

00:01:10.560 problems, and whether you should worry about the way HIIT can raise cortisol in the body.

00:01:15.020 He also shares specific HIIT workouts you can do, including a walking interval workout and

00:01:19.680 one of the best higher-intensity protocols to try.

00:01:22.520 After the show's over, check out our show notes at awim.is slash HIIT, and that's H-I-I-T.

00:01:39.320 All right, Martin Gabala, welcome to the show.

00:01:41.960 Thanks for having me.

00:01:42.920 So you are a professor of kinesiology at McMaster University in Canada, and you spent a lot of

00:01:48.820 your career researching high-intensity interval training, or HIIT.

00:01:54.040 I'm curious, what led you down that path?

00:01:56.380 Yeah, sort of a personal and professional interest.

00:01:58.980 The personal interest is when I first got to McMaster, I was a busy young assistant professor,

00:02:03.980 had a working spouse, two young kids at the time, and so, you know, quite ironically for

00:02:08.920 a professor of exercise physiology, I found myself with very little time to exercise, and

00:02:13.620 that dovetailed with a professional interest.

00:02:15.460 For a long time, I've taught a fourth-year course called The Integrative Physiology of

00:02:20.100 Human Performance, and my students are always interested in the training regimes of high-level

00:02:24.380 athletes.

00:02:25.060 And so I would ask them, you know, why do these elite endurance athletes sprint?

00:02:30.040 Why do they run hard or do these short, intense workouts to enhance their aerobic performance?

00:02:35.240 And so it was those combination of things that led me down this path.

00:02:38.820 I think everyone at this point has probably heard of high-intensity interval training or

00:02:43.280 HIIT.

00:02:43.840 I mean, it really had a moment.

00:02:45.500 I mean, this is about when your book came out, the one-minute workout came out, and you

00:02:48.920 wrote some articles for the New York Times, like, went viral.

00:02:52.040 Like, you could just do a short workout, really intense, and get all these benefits.

00:02:56.940 But I think when most people think of HIIT, and I know I did this before I read your book,

00:03:00.740 they typically think it's got to be a bootcamp style, super intense, crossfit, workout of

00:03:07.200 the day type workout.

00:03:08.600 But one of the points you make in the book is that idea of HIIT, well, that is HIIT.

00:03:13.160 That idea of HIIT is too narrow.

00:03:15.640 So how do you define high-intensity interval training?

00:03:19.500 Yeah, absolutely.

00:03:20.420 And for sure, this idea that you need to go all out or as hard as you can go, that's a big

00:03:25.580 misconception.

00:03:26.260 Certainly, that's one type of high-intensity interval training, but it's not the only type.

00:03:32.440 And so to me, HIIT is very simply alternating bouts of relatively hard work and recovery

00:03:37.700 periods.

00:03:38.620 Now, high-intensity, we can generally equate that with vigorous intensity effort, you know,

00:03:44.000 as compared to light or moderate.

00:03:46.260 And there's well-defined metrics in physical activity, exercise, prescription guidelines

00:03:51.260 for what constitutes vigorous intensity.

00:03:54.520 So if you could imagine a simple 10-point subjective scale where one is laying on the

00:04:01.040 couch or complete sedentariness and 10 is sprint from danger pace or save your child from an

00:04:06.680 oncoming car, vigorous exercise or HIIT is about a seven.

00:04:11.000 It roughly corresponds to about 80% of maximal heart rate.

00:04:15.320 And for an athlete, it means the severe intensity domain.

00:04:18.580 And we use other metrics such as critical power, critical speed.

00:04:21.360 But key point here is that it is not only all-out exercise.

00:04:26.740 Absolute intensity can vary dramatically between individuals, but the relative intensity can

00:04:32.920 be quite similar.

00:04:34.060 Yeah, I think that's a good point.

00:04:34.920 What constitutes intensity is going to vary from person to person.

00:04:37.920 So someone who's super fit, crossfitter type guy, what that person has to do to get to a high

00:04:44.060 enough intensity to have a high-intensity interval training workout, it's going to be different

00:04:48.440 from someone who hasn't worked out or exercised in 30 years.

00:04:51.540 And their intensity might just be they get up off the couch and they walk briskly for a little bit.

00:04:57.040 That's going to be intense for them.

00:04:59.260 Absolutely.

00:05:00.040 There's a figure I like to show in presentations to different stakeholders, and it's two heart rate

00:05:05.380 tracings from two individuals on very far ends of the fitness spectrum.

00:05:09.520 And the top heart rate tracing is from an Olympic athlete, and the bottom tracing is from an

00:05:14.500 individual with coronary heart disease, but they're both doing the same interval training

00:05:20.320 workout normalized to them.

00:05:22.140 They're both doing four-minute intervals at about 90% of their maximal heart rate.

00:05:27.160 Now, of course, the Olympic athlete is working at a very high pace.

00:05:31.360 And as you alluded to, the deconditioned patient is hardly doing much more than a walk or a brisk

00:05:38.980 walk, but it really is a dramatic illustration of this notion that we can really scale absolute

00:05:45.040 intensity to elicit the same relative stimulus, even if people are on very far ends of the

00:05:50.620 fitness spectrum.

00:05:51.700 Okay.

00:05:51.840 So another important part of HIIT is the interval part.

00:05:55.280 So it's not just you're going hard for as long as you can.

00:05:58.640 The idea is that you take a break from it every now and then and then go back up.

00:06:01.860 So you're trying to create just this wave of extremes in your workout.

00:06:06.460 That's right.

00:06:07.620 We talk about hills and valleys and, you know, going back to athletes, you know, a common

00:06:11.680 refrain is make your hard days hard and your easy days easy.

00:06:15.040 And so it's the same notion, right?

00:06:16.700 And those recovery periods are very, very important in order that you can go hard in the subsequent

00:06:22.680 intervals.

00:06:23.140 But this ungenerating pattern is intrinsic to the method.

00:06:27.860 Okay.

00:06:27.960 So basically HIIT is alternating higher intensity bouts of exercise with lower intensity in the

00:06:33.920 same session.

00:06:34.460 And you're alternating because you can't stay very high intensity for long.

00:06:38.180 I mean, the idea is, and we're going to talk about this more as we go along, but by ramping

00:06:43.440 up the intensity, just a few short bouts of exercise can give you a lot of the benefits,

00:06:48.860 just like longer sessions of exercise, but in a shorter amount of time.

00:06:52.700 Yeah, that's exactly right.

00:06:53.900 And so the underlying physiology is the same.

00:06:55.980 You know, your body really does.

00:06:57.240 There's an old saying that your heart doesn't know what your muscles are doing.

00:07:00.840 It just, you know, realizes it's some sort of physiological stress or challenge.

00:07:06.000 And what we're finding is that, you know, intensity really plays a key.

00:07:10.040 And so we can definitely trigger responses through traditional moderate intensity, continuous

00:07:15.900 training, relatively high volume.

00:07:17.780 But many of those hallmark adaptations, it seems we can trigger with a surprisingly small

00:07:23.340 dose of the vigorous intensity work as well.

00:07:26.440 So while HIIT really burst on the scene, I'd say, you know, the middle of the 2000s, early

00:07:31.940 2010s, one thing you do in your book is that you highlight that athletes and other professions

00:07:38.680 like the military as well, they were using HIIT without even knowing they were using HIIT

00:07:44.220 to get in better shape.

00:07:45.800 Yeah, absolutely.

00:07:46.640 So athletes tended to perform high volume, high intensity interval training.

00:07:51.680 And so there's very famous examples of people like Paavo Nermi, Emil Zadopek.

00:07:57.160 These are Olympic champions in multiple events.

00:08:00.660 And for example, legend had it that Zadopek sometimes completed 15 miles a day of intervals

00:08:06.020 as 200 and 400 meter repeats.

00:08:08.600 So these very, very high volume protocols.

00:08:11.740 But also there were individuals like Roger Bannister, who famously trained with intervals on his

00:08:17.960 lunch hour when he was a very busy medical student running repeats on a quarter mile track.

00:08:23.620 And then you also highlight, I thought it was interesting, the Canadian, this is the Air

00:08:26.760 Force or it was one of the military units in Canada.

00:08:29.000 They, this guy stumbled upon HIIT and he used it to help get new recruits in shape.

00:08:34.520 That's right.

00:08:35.120 One of the first exercise physiologists was hired by the Canadian military at sort of the

00:08:40.140 height of the Cold War.

00:08:41.200 Because at one time you can imagine these service members stationed in very remote outposts, you

00:08:46.780 know, literally near the North Pole.

00:08:48.520 And at one time, so many Air Force pilots were unfit, about a third were deemed unfit to fly

00:08:56.760 on missions.

00:08:57.360 And so the government realized they had to do something about it.

00:08:59.960 But, you know, you're stationed in the far North, not a lot of specialized equipment.

00:09:03.560 You don't want to be outside very much.

00:09:04.920 And so they came up with this plan called 5BX, which stood for five basic exercises.

00:09:10.460 And sort of the tagline was you could get fit with these simple bodyweight style exercises.

00:09:15.260 It only took about 11 minutes a day and this spread well beyond the military.

00:09:20.980 And eventually about 20 million of these pamphlets were distributed to Canadian households in

00:09:25.080 the early 1960s.

00:09:26.620 There was an equivalent plan for women called XBX. 0.67

00:09:29.800 But again, it was this idea that you could get fit, didn't have to be fancy, didn't require

00:09:34.200 a lot of time, but it was based on this idea of, you know, getting up to a vigorous pace in

00:09:38.900 order to stress the cardiovascular system.

00:09:41.660 Well, we've been talking about you can use HIIT to get fit, I mean, increase fitness.

00:09:47.020 Let's talk about what we mean by fitness.

00:09:49.000 And in the book, you talk about there's, you know, we have different systems in our body,

00:09:53.200 the anaerobic system and the aerobic system.

00:09:56.900 How does HIIT make us more fit?

00:10:01.200 We're doing a lot of rhyming here.

00:10:02.660 How does HIIT make us more fit, both anaerobically and aerobically?

00:10:06.540 And I guess we'd have to explain what the anaerobic systems are and the aerobic systems 0.97

00:10:10.360 are for those who aren't familiar with it.

00:10:12.260 We'll start there.

00:10:13.180 Yeah, absolutely.

00:10:14.360 So basically two ways of generating energy within the body.

00:10:18.080 And so aerobic means requiring oxygen.

00:10:21.720 So you can imagine we literally are burning fuels such as sugars and fats using molecular

00:10:28.440 oxygen to produce energy.

00:10:29.960 And so very much like a fire, you know, you need wood for the fire.

00:10:32.560 That's the glucose or fatty acid molecules.

00:10:34.640 You need oxygen and you need the spark as well to keep the fire going.

00:10:39.160 Now, we can also produce some energy without the use of oxygen.

00:10:42.800 And so this is the notion of anaerobic or non-oxidative energy.

00:10:46.420 And you could think of a spectrum or a continuum rather, where the aerobic system is great in

00:10:52.040 terms of capacity, very high overall amounts of energy, but it comes at a cost of it's slower.

00:10:58.280 And so non-oxidative or anaerobic energy, it doesn't require oxygen.

00:11:03.160 It's very, very fast in terms of the rate at which it produces energy, but its capacity

00:11:07.000 is very, very limited.

00:11:08.440 And so for a long time, it was thought, or you still hear this very commonly today, that

00:11:13.100 HIIT is anaerobic exercise.

00:11:14.900 And again, very much a misnomer.

00:11:17.700 Any type of repeated sprint is primarily fueled by the aerobic or oxidative energy supply system.

00:11:26.060 And so, you know, you can think of team sports or that, but repeated sprints very much an

00:11:32.620 aerobic stress.

00:11:34.200 And so it's not surprising then that we see these profound responses within the aerobic

00:11:39.040 energy supply system.

00:11:41.200 You know, even during a 30 second, as hard as you can go, all out sprint, about 20% of

00:11:46.240 the energy is coming from aerobic metabolism.

00:11:49.200 And then when you do repeated 30 second all out sprints, the predominant energy providing

00:11:54.560 system is aerobic metabolism.

00:11:57.280 Yeah, that's really interesting because, yeah, I've heard that same thing that sprinting

00:12:00.000 is an anaerobic metabolic conditioning.

00:12:02.460 And if you wanted to get aerobic conditioning, you have to do the more steady state cardio.

00:12:06.460 What do you think is going on there?

00:12:07.700 You know, like why does that idea still exist that sprinting only engages the anaerobic system

00:12:14.240 when sprinting at intervals, at least, you're actually engaging the aerobic system too?

00:12:19.560 Yeah, well, there's no doubt, you know, if you want to become a better sprinter, you better

00:12:22.400 sprint train, right?

00:12:23.440 And so sprint training, it will definitely stimulate non-oxidative energy metabolism and

00:12:28.660 again, literally make you a better sprinter and develop those enzymes in that supply method.

00:12:34.360 It's a fact that when you do a single sprint, most of the energy is anaerobic.

00:12:38.940 But again, it's very, very different when we do these repeated sprints.

00:12:42.540 And so I'm not really sure why that endures so much or we use these terms like aerobic and

00:12:47.840 anaerobic and, you know, another misconception is that we only utilize one system or the other.

00:12:53.440 We're very much, you know, virtually every type of exercise that we do, whether it lasts

00:12:58.440 a few seconds or many, many hours, there's always going to be some blend or some contribution

00:13:02.620 for both of those main systems.

00:13:04.460 And really it's whatever system predominates.

00:13:07.340 But again, suffice to say, repeated sprints, very potent aerobic stimulus.

00:13:11.380 And, you know, that's associated with a wide array of health benefits as well when we develop

00:13:16.580 the aerobic supply system.

00:13:18.480 So what are the aerobic responses our body has when we take part in repetitive sprinting

00:13:24.560 at intervals?

00:13:25.900 Yeah, probably the biggest one is cardiorespiratory fitness.

00:13:29.600 And, you know, that's that notion of cardio health.

00:13:31.800 It's largely determined by the capacity of your heart, your blood vessels to circulate oxygen

00:13:38.020 through the body.

00:13:38.900 We measure that clinically or in a laboratory with a maximal oxygen uptake test.

00:13:44.860 So that's a VO2 max test.

00:13:46.300 That's clearly very important for athletes, but there's very strong and compelling epidemiological

00:13:52.620 evidence to show that having a higher cardiorespiratory fitness is associated with a lower risk of dying

00:13:58.620 from all causes, a lower risk of developing many different chronic conditions like cardiovascular

00:14:03.480 disease, type 2 diabetes.

00:14:05.960 And so any way that we can enhance our cardiorespiratory fitness is really, really important.

00:14:11.360 So you can sort of think of your cardiorespiratory fitness as the ceiling, right?

00:14:14.800 And we want our ceiling to be as high as possible.

00:14:17.240 And then the other aspect to fitness is metabolic fitness.

00:14:20.620 And that's largely determined by our muscles.

00:14:23.020 And that sort of regulates how close to the ceiling you can work for a prolonged period of

00:14:28.100 time or your resistance to fatigue.

00:14:30.260 And so, you know, athletes want high cardiorespiratory fitness and a high metabolic fitness.

00:14:35.400 They want a big ceiling and they want to be able to work close to that for a long time.

00:14:39.020 But it's again, the underlying physiology is the same.

00:14:42.020 And so individuals who are very deconditioned, they often have low ceilings, but they have

00:14:47.480 a very low percentage of the ceiling that they can work at as well.

00:14:52.520 And so any type of exercise training will tend to enhance both of those things.

00:14:56.820 But again, we've learned that the vigorous intensity intermittent exercise can be, you

00:15:01.520 know, we talk about an efficient way to train.

00:15:03.820 What that really means is there's some time efficiency there and we can get away with less

00:15:08.440 total time and probably exercise and still get to a similar level of improvement.

00:15:14.340 Yeah, so you could do an hour of steady state cardio and get, you know, X amount of benefits

00:15:20.140 in terms of VO2 max or increase in mitochondria in your cells, or you could do a 10 minute high

00:15:26.420 intensity interval training and get roughly the same benefits.

00:15:31.040 Is that the pitch, the sales pitch?

00:15:32.760 Yeah, no, it is, right?

00:15:33.860 And, you know, arguably we should do both.

00:15:35.620 And, you know, you very much see these arguments where people will try to demonize traditional

00:15:40.600 cardio or now there's sort of a pushback against HIIT.

00:15:43.300 You know, I really have a ton of time for those.

00:15:45.700 Try to say, you know, what is the best type?

00:15:47.960 Again, I think at least from our research, what we've been trying to do, we talk about

00:15:51.940 expanding the movement menu, which really means, you know, we've largely been telling people

00:15:56.160 to do the same thing for a long time and that's fine.

00:15:58.900 The physical activity guidelines are based on excellent science, but we know a lot of people

00:16:03.420 aren't listening, right?

00:16:04.580 And one of the perceived barriers, whether it's real or not, is a perceived lack of time or

00:16:10.040 people think, oh, if I don't have an hour in the day, I'm going to blow off my

00:16:12.540 workout.

00:16:13.480 And I think what the interval training literature is showing is, you know what, you don't need

00:16:16.840 a whole lot of time and still get some bang for your buck there. 0.97

00:16:20.880 And really that's been our, the focus or a focus or through line of our research is,

00:16:25.500 you know, trying to establish the scientific credibility of these brief, vigorous type

00:16:30.320 workouts.

00:16:31.020 And then, you know, hopefully presenting that as an option to people.

00:16:34.300 We're not saying it's the only work that you should do or, you know, if you don't like

00:16:37.060 interval training, okay, that's fine.

00:16:38.580 Go do the moderate stuff, but trying to expand that movement menu, give people more physical

00:16:43.680 activity options.

00:16:44.540 Just like we try to give options for dietary strategies, you know, pick the food you like.

00:16:49.440 You can sort of pick the exercise approaches that you like because the best one is what

00:16:53.120 you enjoy.

00:16:53.700 You're more likely to stick with it over the longterm.

00:16:56.120 It seems like people keep rediscovering HIIT or interval training, you know, every 10 years

00:17:01.100 or so.

00:17:01.600 You see this in the fitness industry.

00:17:03.080 You'll see these trends where like, oh, it's steady state cardio.

00:17:06.500 Like, no, no, no.

00:17:07.840 We're going to do HIIT now.

00:17:08.980 It hits the best thing in the world.

00:17:10.120 Like, no, actually it's steady state cardio.

00:17:12.180 Because I think in the past five years, I've seen a lot of talk about zone two cardio where

00:17:16.840 it's, you know, you want to stay in zone two for 60 minutes and get so much of it a

00:17:22.100 week.

00:17:22.640 And I've been doing that.

00:17:23.700 I've, I've enjoyed it.

00:17:24.480 It allows me to watch movies and television shows that I don't otherwise wouldn't watch.

00:17:28.580 But I think what your research is showing is that there's nothing wrong with zone

00:17:31.800 two cardio, it's very healthy for you.

00:17:34.220 But if you don't have time, HIIT might be an option for you.

00:17:37.940 No, I agree.

00:17:38.500 And so, you know, I think some of the, and you're right, you know, these things come in

00:17:41.680 and out of fashion a little bit, but I think some of the pushback against HIIT comes certainly

00:17:46.720 from some overstatement regarding potential benefits of HIIT, you know, hopefully not from

00:17:51.080 our laboratory or interviews like this, but definitely, you know, see, you see some overstatement.

00:17:55.640 You can get away with a few minutes a week and, you know, that's the solution for

00:17:58.820 fitness or, so when we start saying, you know, this is the solution to our inactivity

00:18:03.180 problem, or this is the best way to exercise or the optimal approach, I, I think that's

00:18:08.480 where it becomes problematic.

00:18:10.060 You know, to my mind, the rise of zone two is owing in part to, that's how high level

00:18:16.580 endurance athletes train in terms of a roughly an 80-20 split.

00:18:21.720 So if you're a high level endurance athlete, you know, training 25, 30 hours a week, there's

00:18:27.240 very good evidence to show that they tend to center around this 80% low intensity, 20%

00:18:34.860 high intensity, much of that being intervals.

00:18:37.960 And so, you know, it's interesting because classically zone two has meant the heavy intensity

00:18:43.960 domain, and this is where there's a classic three zone training model for, for athletes.

00:18:48.040 But, you know, now zone two has commonly been interpreted as low intensity, sublactate

00:18:54.700 threshold based training.

00:18:56.880 And you're right, you know, it's, it's definitely can be beneficial.

00:19:00.180 You know, I'm, I'm unconvinced or I just don't see the data that zone two is best to optimize

00:19:06.040 your mitochondrial capacity.

00:19:07.640 There's many different ways to do that.

00:19:09.460 And so I think, again, ideally we should train across a range of intensities, but I'd come

00:19:15.560 back to this idea that I think as, as volume decreases, intensity is arguably more important.

00:19:22.880 And so where I would take some exception to the commentators is suggesting that because

00:19:27.840 athletes who do 25 hours a week train this way, that's how everyone else should exercise,

00:19:34.720 you know, regular people who might have an hour a week or, you know, two hours a week

00:19:39.800 to exercise, or maybe they only have 20 minutes that they're willing to do.

00:19:43.400 I think they're doing anything is clearly better than nothing, but engaging in a more vigorous

00:19:49.640 effort, again, not necessarily all out.

00:19:51.840 It's better bang for your buck, certainly given the time investment.

00:19:54.820 Yeah.

00:19:54.840 I know I made a big emphasis on zone two starting two years ago because the, the, the sales pitch

00:20:00.460 on, oh, it helped increase the amount of mitochondria in your cells.

00:20:04.080 I was like, well, that sounds like it's important.

00:20:06.040 And so I'm doing two to three hours a week on the elliptical watching Cobra Kai on YouTube,

00:20:12.300 but I'd have days where I couldn't get a session in a zone two sessions.

00:20:15.960 Like, man, it's an hour.

00:20:16.660 I don't have an hour.

00:20:17.760 And so I just wouldn't work out.

00:20:19.180 It's like, well, I'm not going to get that mitochondria that I need.

00:20:21.820 But then after I read your book, this happened to me last week.

00:20:24.440 I didn't have time.

00:20:25.540 I had literally had 15 minutes.

00:20:27.740 So I just got on my airdyne bike, the fan bike, and I did a interval thing.

00:20:33.440 I was like, Hey, I got it.

00:20:35.860 And I got some, I got some of those aerobic benefits from doing that 10 minute interval

00:20:39.560 training workout.

00:20:41.220 Fantastic.

00:20:41.520 Right.

00:20:41.720 And that's the key takeaway, I think is lots of different options, even for a given individual,

00:20:45.940 you know, I'm, I'm a committed exerciser to this approach.

00:20:48.860 Well, if I can't do my approach on that day, maybe I'm going to try something different.

00:20:53.180 And so again, vary it up.

00:20:55.380 And, you know, to your point, when time is pressed, maybe engage in some of the vigorous

00:21:00.360 stuff.

00:21:00.700 And even, even if only you do it for five or 10 minutes, know that you're still getting

00:21:04.500 some benefit there, at least to maintain your fitness, you know, until you can get back

00:21:08.660 to your regular routine.

00:21:10.140 Okay.

00:21:10.220 So hit, you can get the same aerobic benefits as doing the long and slow and steady cardio.

00:21:16.200 I think that's good to know.

00:21:18.320 I mean, you talk about how it can improve our cardiovascular health, reduce, you know, our

00:21:22.540 risk of heart attacks, heart disease.

00:21:24.740 I mean, you also at how hit can help improve or manage diabetes and insulin resistance.

00:21:30.320 What does your research say there?

00:21:32.480 Yeah.

00:21:32.780 And so again, I want to be, you know, I want to really emphasize here, any type of exercise

00:21:37.300 can do these things, right?

00:21:39.360 And so these are not necessarily exclusive benefits to hit, but certainly some evidence from our laboratory,

00:21:45.340 a lot of other laboratories shows that hit can improve measures of insulin sensitivity

00:21:51.020 or blood sugar control.

00:21:53.060 And so part of the reason for that is that, you know, we have in our body, these things

00:21:57.780 called glucose transporters.

00:21:59.600 They're in all of our tissues, but they're responsible for sort of moving the glucose molecules

00:22:03.620 or the sugar out of the bloodstream into our cells, or it can be taken up and stored or

00:22:08.440 used for energy.

00:22:09.440 And so exercise generally, and in particular vigorous exercise, enhances the capacity for

00:22:15.160 glucose transport.

00:22:16.460 And so that's likely one of the reasons that blood sugar control can be managed a little

00:22:21.080 bit better.

00:22:21.460 Or certainly if you're an individual with type 2 diabetes and you engage in regular exercise,

00:22:25.940 one of the things that you'll find is your physician is going to say, well, you need less

00:22:29.000 of your medication because the exercise is doing that for you.

00:22:32.740 And so we don't now need to give you drugs or as many drugs in order to try and regulate

00:22:37.280 your blood sugar because you're sort of doing it on your own through physical activity.

00:22:40.620 Another benefit I've seen touted for HIIT is weight loss, this idea of the afterburner

00:22:46.020 effect.

00:22:46.980 What does the research say about that?

00:22:48.360 Is that legit?

00:22:49.620 Yeah, definitely something to it.

00:22:51.480 Again, it's one of these things I think that's often overstated.

00:22:54.380 And so, you know, you look online and you might see someone's comparing an interval versus a

00:22:59.060 traditional cardio workout and see this massive afterburn effect.

00:23:03.180 It's definitely real.

00:23:04.360 So this idea of a heightened metabolic rate in recovery, you have this transiently higher

00:23:09.260 calorie burn and it can add up over time.

00:23:12.780 So people say, you know, how can HIIT, especially if it's short, result in any calorie burning

00:23:18.020 at all?

00:23:18.500 Well, it does relate to this idea of the afterburn effect.

00:23:22.220 But again, it's relatively small and we shouldn't overstate it.

00:23:25.860 And, you know, HIIT can play a role in weight management efforts, just like other types of exercise.

00:23:30.120 But, you know, the nutrition side of the equation is the primary driver there.

00:23:34.360 We're going to take a quick break for your word from our sponsors.

00:23:41.540 And now back to the show.

00:23:43.460 Okay, so HIIT can improve our aerobic capacity. 0.89

00:23:46.000 It can improve our cardiovascular health, can help with insulin sensitivity, with weight

00:23:50.040 loss.

00:23:50.920 How much HIIT do you have to do to get these benefits?

00:23:54.580 Like how long do the sessions need to be?

00:23:57.100 And like how many sessions do you have to do before you start seeing these benefits?

00:24:01.340 Have you guys looked at that?

00:24:03.140 Yeah, we have.

00:24:03.620 And so definitely the responses, the adaptations, they can occur surprisingly quickly.

00:24:09.260 So we're talking within a week or two, you know, we've done a study, for example, in

00:24:13.700 older overweight individuals with type 2 diabetes, and we put them on a HIIT protocol that was

00:24:20.160 only six sessions over two weeks.

00:24:22.420 And even after two weeks, we saw marked improvements in some of those things that I was talking about,

00:24:27.440 their glucose transport capacity, some markers of blood sugar control.

00:24:31.860 So the responses can occur very quickly.

00:24:35.080 And probably the more deconditioned you are, the faster the response is, you know, you probably

00:24:40.820 have a lot more room to improve.

00:24:43.700 We've got to be careful there because, you know, we're not saying to these people that,

00:24:47.600 especially if you're very deconditioned, HIIT does not mean jumping off the couch and pedaling

00:24:51.520 your heart out on a bike.

00:24:52.520 It's just, you know, getting out of your comfort zone, going a little harder than you may have

00:24:56.380 before.

00:24:56.960 So it definitely can occur quickly in terms of how long the sessions have to be.

00:25:02.700 Again, this is where it really comes back to what's the intensity.

00:25:05.420 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.

00:25:23.320 And just to recap, the intensity we're going for is on a scale of one to 10.

00:25:28.060 Seven is about what we want to hit.

00:25:30.360 That's right.

00:25:31.020 Seven out of 10 is that vigorous range.

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?

00:25:47.280 Yeah.

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

00:26:08.480 to know you might be in the right range.

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

00:26:20.340 don't seem to align as well.

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

00:27:06.220 the duration can be.

00:27:07.220 Is that correct?

00:27:08.580 Yeah.

00:27:08.840 You know, there's clearly an intensity duration trade-off.

00:27:11.660 It's not necessarily linear either.

00:27:13.480 It's, it's almost exponential.

00:27:15.120 So as the intensity really gets up there, the dose that you need, the volume or the time

00:27:21.360 that you need can really, really drop off.

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?

00:27:32.920 Yeah.

00:27:33.320 So I, there's definitely some differences related to biological sex, but they appear

00:27:40.120 to be quite subtle.

00:27:41.600 There's a much greater range or scale for just fundamental inter-individual differences

00:27:48.280 between humans.

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 1.00

00:28:12.700 a cardiovascular response as males.

00:28:15.580 But again, I think that's more related to just inter-individual differences between humans

00:28:21.280 or that's much broader.

00:28:23.440 And clearly both men and women can benefit from interval training and benefit from, you

00:28:28.020 know, many different types of exercise.

00:28:29.940 What about age and HIIT?

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

00:28:37.200 I might have a heart attack or something.

00:28:39.280 Is there any risk to HIIT if you're older?

00:28:41.940 Yeah.

00:28:42.220 So I like, you know, and to that specific example, no one has to do HIIT if they don't

00:28:47.280 like it or prefer it, right?

00:28:48.660 So there's a couple of ways to look at this.

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

00:29:12.340 or high intensity work.

00:29:14.800 But again, when we look at the guidelines, adults of all ages are recommended to do vigorous

00:29:20.780 intensity exercise.

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

00:29:35.080 factors.

00:29:35.600 And so, you know, the standard advice, of course, is that people should see their doctor if they're

00:29:40.860 going to start or change an exercise regime.

00:29:44.020 Start slowly, right?

00:29:45.260 So if you're just getting into exercise, physical activity, start with the moderate stuff, then

00:29:49.560 add the vigorous stuff.

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

00:30:03.960 safely.

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

00:30:33.420 really suited to you and you're suited for it.

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

00:30:57.800 patients.

00:30:58.140 They're not going to do the all-out 10 sprint, but they're getting their patients to do vigorous

00:31:03.540 exercise in a supervised manner.

00:31:06.640 Because what the studies have found is that it helps strengthen these people's hearts that

00:31:10.940 have gone through a heart attack.

00:31:12.900 Yeah, that's exactly right.

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

00:31:23.660 lift a weight.

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.

00:31:31.680 Ideally, it's properly supervised.

00:31:34.220 But, you know, and it depends across the world.

00:31:37.200 Everyone's reading the same science.

00:31:38.540 But, you know, for example, in Scandinavia, I think interval training is much more an accepted

00:31:43.360 part of cardiac rehab practice.

00:31:46.360 We're a little bit less, I would say, in North America.

00:31:49.640 And, you know, and that's fine.

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?

00:32:01.760 Maybe a bit.

00:32:03.960 You know, I'm less concerned or I'm not convinced sort of these acute fluctuations in hormones

00:32:10.620 post-exercise matter that much.

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

00:33:04.840 exercisers to keep exercising?

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.

00:33:36.620 You know, I don't subscribe to that notion.

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.

00:34:03.580 I'm getting the same benefit.

00:34:05.200 I'll take that.

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

00:34:38.360 is not very great.

00:34:40.140 And so to demonize any form of physical activity doesn't make sense to me if arguably we're all

00:34:46.720 in the same team here.

00:34:47.900 And we agree that the biggest thing that we need to do is just get more people active

00:34:53.680 and more people moving.

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.

00:35:32.180 That's fine.

00:35:32.780 You're getting all these great health benefits doing that.

00:35:35.840 A hundred percent.

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

00:35:40.700 empowering way to exercise.

00:35:42.600 It's like, no, no, wait a minute.

00:35:43.720 You're not a failure because you can't sustain a pace for 30 minutes.

00:35:47.260 You're training like Olympic champions.

00:35:49.060 That's what they do.

00:35:49.680 They sort of go hard, they take a break, and they do it again.

00:35:52.160 So, you know, that's completely okay.

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.

00:36:06.320 So, you know, keep it up.

00:36:07.600 I love that.

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

00:36:34.260 minutes of work.

00:36:35.900 I think that's how people should look at it.

00:36:37.380 It's an option.

00:36:38.320 It's a particularly time-efficient option.

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?

00:36:55.120 Almost anything.

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.

00:37:52.180 Correct.

00:37:52.680 Yeah.

00:37:52.980 So, what's a good interval workout for, I get to say, a rank beginner?

00:37:56.940 Yeah.

00:37:57.400 So, two ways to answer this question.

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

00:38:22.660 back off.

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.

00:38:38.860 Again, we're just talking brisk walking here.

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.

00:38:50.860 And then, you know, you go from there.

00:38:53.160 And what tends to happen is the intensity goes up and the duration of the intervals goes

00:38:58.920 down.

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

00:39:06.580 protocol.

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?

00:39:19.380 And I don't think it matters, right?

00:39:21.080 Again, generally speaking, unless you're an athlete training for a very specific performance

00:39:25.660 outcome.

00:39:26.340 For most of us, it doesn't matter.

00:39:28.280 And hopefully, that's empowering.

00:39:29.760 And hopefully, you know, it takes away the boredom a little bit because, you know, vary

00:39:33.600 up the intervals.

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.

00:39:38.480 But with intervals, you can really vary it up.

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

00:39:55.760 spectrum.

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

00:40:07.480 the complete other end of the spectrum.

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.

00:40:30.380 Okay.

00:40:30.540 So, yeah, the key takeaway there is the more intense you go, the shorter your workout can

00:40:35.720 be.

00:40:36.260 But the less intense, if you're doing just a walk, your intervals will have to be longer.

00:40:41.040 And so, your workout overall will take longer.

00:40:43.560 That's right.

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.

00:40:51.060 And that's not necessarily for everyone.

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,

00:41:04.280 you know, three, four, or five times.

00:41:06.480 One you highlight that I like is the Wingate Classic.

00:41:11.300 What's that one about?

00:41:12.580 Yeah.

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

00:41:30.440 gives back just what you're able to put out.

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

00:41:54.440 Wingates with a few minutes in between.

00:41:56.580 These were very, very demanding workouts.

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,

00:42:09.020 and looked at other protocols.

00:42:10.500 Yeah.

00:42:10.640 You have the, it's the 10 by 1 is your variation of the Wingate.

00:42:14.620 That's right.

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.

00:42:34.240 At least they're not all out.

00:42:35.760 And then more recent research by others has shown that, you know, 5 by 1 can be almost

00:42:41.260 as good as 10 by 1.

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

00:42:49.180 only 5% better.

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.

00:43:09.860 Right.

00:43:10.000 So yeah, the 10 by 1, just for listeners, your first sprint is at an intensity of 5.

00:43:15.100 You do that for a minute.

00:43:16.300 Then you rest one minute for recovery.

00:43:18.780 Then your second sprint is going to be at a slightly higher intensity level.

00:43:22.900 So 6, do that for a minute.

00:43:24.940 And then you just keep that cycle going until you get to an intensity level of 9.

00:43:30.320 That's right.

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,

00:43:39.100 intensities or that.

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?

00:43:48.880 For the intervals.

00:43:50.700 So, you know, whatever.

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

00:43:58.520 like a 5 out of 10.

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.

00:44:10.120 Okay.

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

00:44:14.840 I move through the workout.

00:44:16.300 So your book is called The One Minute Workout.

00:44:18.160 It's a catchy title.

00:44:18.940 I'm sure the publisher, your editor is like, we got to call this The One Minute Workout because

00:44:22.460 it's going to sell books.

00:44:24.020 But is there a workout that lasts about a minute that can give you all these health

00:44:27.920 benefits we've been talking about?

00:44:29.520 So, yes.

00:44:30.980 And I'll get to that in a minute.

00:44:32.380 But you're right.

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

00:45:07.180 minute or less.

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

00:45:20.760 night for the subway.

00:45:22.220 You know, you exercise at a vigorous pace to get to the subway rather than a pedestrian pace.

00:45:27.860 And so that's known as an exercise snack.

00:45:30.140 And you sprinkle these through the day.

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

00:45:52.680 to it earlier.

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

00:46:24.560 to get to the subway.

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.

00:46:37.440 And that takes you about a minute.

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

00:47:11.780 physical activity through the day.

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

00:47:31.100 our health.

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

00:47:41.580 the middle there.

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?

00:47:57.540 All right.

00:47:57.880 So the takeaway there, take the stairs.

00:48:00.140 Absolutely.

00:48:00.700 Take the stairs.

00:48:01.560 A few minutes of vigorous effort a day really, really pays benefits and it feeds into the

00:48:05.980 notion that every little bit counts.

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?

00:48:13.480 Yeah, sure.

00:48:13.960 So I do have a website, martingabala.com and sort of that's a one-stop shop for, you know,

00:48:18.940 other podcast interviews like this.

00:48:20.520 People learn about the book.

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.

00:48:30.200 Fantastic.

00:48:30.660 Well, Martin Gabala, thanks for your time.

00:48:31.720 It's been a pleasure.

00:48:32.840 Thank you.

00:48:34.640 My guest today was Dr. Martin Gabala.

00:48:36.360 He's the author of the book, The One Minute Workout.

00:48:38.580 It's available on amazon.com.

00:48:40.440 Check out his website at martingabala.com where you can find more information about his

00:48:43.380 work.

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

00:49:12.560 think of.

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

00:49:16.300 review on the podcast or Spotify.

00:49:17.700 It helps out a lot.

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00:49:20.660 Please consider sharing the show with a friend or family member.

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00:49:24.280 As always, thank you for the continued support.

00:49:26.840 Until next time, I'm Brett McKay reminding you to listen to AOM podcast, but put what you've

00:49:31.180 heard into action.

00:49:32.080 All right.

00:49:33.360 You.

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00:49:44.920 Thank you.

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00:49:57.340 Thank you, everybody.

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The Art of Manliness - February 28, 2024

The Misconceptions of HIIT (And the Role It Can Play in Your Fitness Routine)

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