#293 - AMA #57: High-intensity interval training: benefits, risks, protocols, and impact on longevity

0:10Hey everyone, welcome to a sneak peek, ask me anything, or AMA episode of the Drive Podcast. I'm your host, Peter Atia. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created. Or you can learn more now by going to peteratia MD dot com forward slash subscribe. So without further delay, here's today's sneak peek of the Ask Me Anything episode.

0:39Welcome to Ask Me Anything episode 57. I'm once again joined by my co -host Nick Stenson. In today's episode, we dive deep into the topic of hit, high intensity interval training. This is a topic we get asked about a lot, and it seems that there is a lot of confusion around both the semantics of this and perhaps more importantly, the data. So in today's AMA, we cover what exactly hit is and what the different types are. When is hit beneficial and when is it not, especially if you're looking through the lens of longevity. The importance of broadening your portfolio of exercise training, and we talk about the best protocol if you're going to use hit.

1:19Throughout this conversation, we also speak about VO2 max and what a person can do to increase the VO2 max, which is something we know is a very important metric for longevity and of course how does hit training factor into that. If you're a subscriber and you want to watch the full video of the podcast, you can find it on the show notes page and if you're not a subscriber, you can watch a sneak peek at the video on our YouTube page. So without further delay, I hope you enjoy AMA number 57.

1:51Welcome to another AMA. How you doing? Very well, thank you. Awesome. Well, today's episode is going to be exercise related, but kind of on a topic that we get asked about a lot and we haven't really covered, which is hit or high intensity interval training. And it's something that people see everywhere. It's marketed a lot. People talk about it. And so we see a lot of questions come through on people who are wondering more about it. What are the different types? How does interval training fit in? and where can it be used? Where's it limited? What's the quote unquote best protocol? And I think we gathered a lot of those questions which we'll cover today.

2:26And through it, I think we'll also hopefully talk a lot about how someone can increase their VO2 max as well, which is something that we've talked a lot about the importance of VO2 max and a lot of people who are thinking about their longevity, it's something that they'll want to increase, so we'll hit on that. And then also, no surprise to people. We'll also, I'm sure, talk about the importance of having a broad exercise program and training and not just specifically focusing on one thing. So we have a lot to do with that said, anything you want to add before we hit the first question. No pun intended.

2:59I think that's great. I think there's a lot to cover here. This was a subject matter that we had been kicking down the road a little bit because because we couldn't wrap our head around the right way to present it. And I feel like it really kind of came together in the last couple of weeks. I feel much better about this subject matter. So I'm glad we waited until we had the data that we've got, the studies that we've been able to look at, and then obviously the implications so that we make this much more rooted in what do you need to do as opposed to making sure you understand every molecular pathway of hit?

3:34Yeah, I think that's correct. And I think it would help to start off with just talking about the word hit because hit is such a commonly used word when people talk about exercise. Can you maybe set the stage of where it even comes from? Yeah, this is something I was kind of curious to learn about as we were getting ready to prep for this because I learned a little bit of this stuff when I was writing out live and it actually didn't make the final cut in the spirit of half this stuff. If you end up writing in the first ref, it's on the cutting room floor. So it was kind of fun to go back to some of this stuff, but this stuff gets documented as far back as the 1800s, which in some ways seems like a long time ago, in some ways is not obviously, but given the relative posity of time that we have serious training, I would say that this is a long time.

4:22And basically what it comes down to is some documentation of athletes having altered their tempo between running and walking for their training. But it wouldn't really be until kind of the early 1900s that it would be codified more seriously. You would originally go back to kind of the finish Olympic runners that first employed this type of training. And many who's done any running or interval training might be familiar with the term fart lick, F -A -R -T -L -E -K, which I believe was coined in the 1930s. It comes or is derived from the Swedish language and I think it refers to playing or speed play or something like that.

5:01So when I was actually growing up, we referred to it as speed play. So alternating fast and slow. I was suspect that a bunch of people listening to us are probably familiar with a type of interval known as Tabata training. So a Tabata interval is a very specific type of interval. This was first described in the 1990s where a guy by the name of Tabata was the first author on a paper that first presented this. I think it was in the mid 90s. Interestingly though, the protocol seems to have been developed by a guy named Irsawa and the interval was eight sets of 20 seconds on a bike all out interval with 10 seconds of rest.

5:43So you're 20 seconds on, 10 seconds off, eight times, which gives you a four minute duration. And anyway, so I didn't learn about a Tabata probably until 10 years later when it was something that one of my cycling coaches employed many many years later. So that's kind of the very very short abbreviated version of how these interval trainings have come along. Another follow up to that is there seems to be a lot of different programs, classes, gyms that call themselves hit training. And we see a lot of questions from people who are confused by this. And so I think it'd be helpful is can you speak a little bit about what hit training actually is and Is there a way for people listening or watching to be able to differentiate between the different types of forms that they may see out there?

6:34Yeah, hit definitely has a bit of a brand issue. By the way when we're saying hit I should clarify its H I I T So high intensity interval training and I think part of the problem with everything we're about to discuss today at least a big part of it stems from the fact that there's no uniform definition in what constitutes hit. Now what I'm going to try to suggest today is that we be a little bit more specific and we differentiate between, for example, high -intensity interval training or hit versus sprint interval training or sit or things like Tabata training, which kind of are a bit of a subset of sit.

7:11The reason for that is they produce very different metabolic effects. They're obviously carried out very different intensities And by extension, they have some sort of different pros and cons. So given that the majority of the literature is on what is called hit, we're going to kind of start with that. But again, if you remember nothing else from this podcast, remember that when someone is talking to you about hit, ask them to stop using the language and just be specific, which is what is the effort level, what is the duration of work, what is the duration of rest, how often do I repeat it, how many times we do it, it's really getting specific that's going to be relevant.

7:52And obviously that's what we want to cover today. Nevertheless, hits are typically defined as sub -maximal efforts. So sub -maximal would be generally 80 to 95 % of a person's maximum heart rate. But I will just tell you right now, out of the gate, I think that definition is not that helpful. Because for example, when I do my zone two, I'm doing it at 80 % of my max heart rate, not because I'm targeting that, but because that's the heart rate I end up being at when I'm in zone two. Well, that's clearly far from sub -maximal. And conversely, 95 % of max heart rate is truly a huge effort. These efforts cover very different energy systems, but again, the purpose of hit is generally to put you in your maximum aerobic training zone, but clearly the duration of the interval, and clearly the intensity will speak to how much anaerobic training you're getting in there as well.

8:52We'll unpack this a lot more, but let me just move on and now talk about sprint interval training. So sprint interval training in some ways, I think, is easier to understand because it is super a maximal. So these are efforts that would exceed the output of your VO2 max. So again, if we think about what VO2 max is, VO2 max is the maximal consumption of oxygen. So this is typically performed at a very high level, but not a peak level. So an all out 30 second sprint does not produce maximal O2 uptake. It's typically going to need to be a duration that's longer than that. So let's just assume you've achieved the level of VO2 peak or VO2 max, you would then say, well, what was my power at that level or what was my speed at that level?

9:41And then sprint interval training is done at an effort that exceeds that. So it's a higher power or a higher speed. Now, here's what's interesting. It's not necessarily a higher heart rate. And the reason for that is that if you imagine what your heart rate is doing at a VO2 max, you've taken a while to get up to that speed or that power, whatever it is you're using. And you're holding it for a couple of minutes. It really gives your heart rate a chance to peak. So when I'm doing VO2 max intervals on the bike, which I'm only doing once a week, I'm almost hitting max heart rate by the end. I'm probably within five beats of max heart rate.

10:18That's actually a higher heart rate than if I'm doing 20 second all -outs on a Tabata. Because in that short period of time, and again, the sprint interval protocols are typically 10 second, 20 second all -outs. In fact, I think they're defined as up to 60 seconds, but you can't do anything all -out at nearly that duration. You typically don't get your heart rate as high, and so they're typically done pegged to a power level or a speed level that is in excess of your peak VO2 max. Hopefully that kind of provides the right amount of clarity on maybe some of the distinction between hit and sit. Yeah, and I think we'll get to, like you said, a lot of the other stuff on the details with the later upcoming questions.

11:05Maybe one other thing I want to say, Nick, though, do you remember when I had Alex Hutchinson on the podcast two years ago, three years ago now? There's something very interesting that Alex Hutchinson wrote about in his book Endor, which is around the science of endurance. And I find this to be completely true for me, which is the only effort in which you can truly go all out is an effort up to about 10 seconds. And that might sound crazy, because I'm sure there are people listening to this. You say, what are you talking about, man? I do 60 second all out bursts. I do 20 second all outbursts, 30 second all outbursts.

11:42I don't think you do. I think if you're doing anything over 10 seconds, you are consciously or subconsciously applying some governor to that activity that keeps you from absolutely blowing up. And I know this, Alex, go through the science of this, but I can just tell you personally that there's a very big difference in how hard I'm able to push when I do a 10 second on, 20 second off repeat versus a 20 second on, 20 second off or 20 second on, 10 second off repeat. And I'm very attentive to how much am I pushing without a limit and anything above 10 seconds, I seem to be just holding back slightly.

12:27So keep that in the back of your mind when people talk about the term all out, that's a very misleading term. real quick you want to know a fun fact about the Alex Hutchinson podcast sure it was the very first podcast we've ever done on video outside of one or two random ones before but when we made the switch to video Alex was the first person that we did that with very interesting another thing real quick before we move on you mentioned max heart rate so I think kind of how you defined all that was really good can you let people know how they would know their max heart rate as well because I think it is going to be a metric that if anyone's kind of looking at this, they're going to want to know to really fully understand how this works.

13:07Yeah, Max heart rate is a pretty literal term. It's the maximum achieved heart rate. Now there are different ways to predict it. The most simple formula that is generally used is the 220 minus your age formula. So if you're 50, your maximum heart rate would be expected to be 170 beats per minute. But a lot of factors play into it. and I don't think that the formula is sufficient. And therefore, I think the only way to really know it is to actually push yourself in sub -maximal efforts until you get to maximum heart rate. So this will typically be seen if a person does a VO2 max test and certainly will be seen if a person does a stress test if they're pushed to failure.

13:50But nevertheless, it is a good heart rate to know if you want to base any of your training on heart rate. I don't personally pay attention to it because everything I'm doing is either based on RPE or Watts and I'm using the Watts to drive This sort of training interval, but some people do use heart rate. I don't think there's anything wrong with that But I don't think it's as robust frankly as speed or Metz or Watts Moving on I think it'd be helpful to just maybe cover or why we probably see so many questions about hit. And I think the reason is, you often see it touted as like a more efficient white exercise or more effective white exercise.

14:32So do you maybe want to talk about why people are out there kind of making that claim as it relates to hit? Thank you for listening to today's sneak peak AMA episode of The Drive. If you're interested in hearing the complete version of this AMA, you'll want to become a premium member. It's extremely important to me to provide all of this content without relying on paid ads. To do this, our work is made entirely possible by our members, and in return, we offer exclusive member -only content and benefits above and beyond what is available for free. So if you want to take your knowledge of this space to the next level, it's our goal to ensure members get back much more than the price of the subscription.

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