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

In this “Ask Me Anything” (AMA) episode, Peter delves into the topic of high-intensity interval training (HIIT), starting with addressing some common misunderstandings around this type of exercise and breaking down what HIIT truly entails. He examines the correlation between HIIT and VO2 max, a vital metric for overall health and longevity, and describes the beneficial impact of HIIT on longevity when incorporated properly. Additionally, he emphasizes the importance of building a wide base of cardiovascular fitness, reveals the optimal protocols for incorporating HIIT into a balanced routine, and discusses the risk of injury and other potential drawbacks of HIIT. 

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We discuss:

• Common questions about high-intensity interval training (HIIT) [1:30];
• The origins of HIIT [3:15];
• Defining HIIT training and differentiating it from sprint interval training (SIT) [5:45];
• Why HIIT is often touted as a more efficient way to exercise [14:00];
• Navigating the nuances of HIIT research: understanding limitations and the importance of a blended exercise routine [20:30];
• The four pillars of exercise [24:15];
• Using HIIT to improve VO2 max [26:00];
• HIIT training for the untrained individual: impact on VO2 max and the interplay between exercise-induced adaptations and potential weight loss [33:00];
• Sprint interval training (SIT) vs. HIIT: comparing the relative improvements in VO2 max and the impact of longer duration intervals [40:00];
• Benefits and limitations of HIIT, drawbacks of overtraining with HIIT, and the importance of a diversified routine to increase total cardiorespiratory capacity [44:15];
• HIIT protocols Peter recommends [58:45];
• The risk of injury and other potential drawbacks of HIIT [1:02:15];
• The importance of incorporating a balance of continuous moderate-intensity cardio and HIIT when aiming for longevity [1:04:00]; and
• More.

Common questions about high-intensity interval training (HIIT) [1:30]

Today’s episode is going to be exercise-related, but on a topic that we get asked about a lot and we haven’t really covered, which is HIIT, or high-intensity interval training.

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 around people who are wondering more about it.

• What are the different types? 
• How does interval training fit in? 
• Where can it be used? 
• Where is it limited? 
• What’s the “best” protocol?
• We’ll also hopefully talk a lot about how someone can increase their VO2 max (which has a lot of importance for people who are thinking about their longevity)
• We’ll also talk about the importance of having a broad exercise program and training, and not just specifically focusing on one thing

Anything you want to add before we hit the first question?

• Peter says that this was a subject matter that he had been kicking down the road a little bit because he couldn’t wrap his head around the right way to present it
• But he feels like it has finally sort of come together in the last couple of weeks
• He’s glad they waited until they had the data and the right studies 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 HIIT.

The origins of HIIT [3:15]

HIIT is such a commonly used word when people talk about exercise. Can you maybe set the stage of where it even comes from?

• There is some documentation from as far back as the 1800s of athletes who would use a combination of running and walking for their training (runners or long-distance walkers)
• What it comes down to is some documentation of athletes having altered their tempo between running and walking for their training
• It wouldn’t really be until kind of the early 1900s that it would be codified more seriously
• You would originally go back to the Finnish Olympic runners that first employed this type of training
• The term FARTLEK, coined in the 1930s, is derived from the Swedish language which may translate to something like “speed play”
• When Peter was growing up, they referred to alternating between fast and slow as “speed play”

Tabata

• Another familiar term is Tabata training
• A Tabata interval is a very specific type of interval 
• This was first described in the 1990s where a guy by the name of Izumi Tabata who was the first author on a paper that first presented this
• Interestingly, though, the protocol seems to have been developed by Olympic speed skating coach Koichi Irisawa 
• The interval was eight sets of 20 seconds on a bike, all-out interval with 10 seconds of rest, so you’re 20 seconds on, 10 seconds off, eight times, which gives you a four-minute duration

Defining HIIT training and differentiating it from sprint interval training (SIT) [5:45]

A lot of different programs, classes, gyms that call themselves HIIT training

Can you speak a little bit about what HIIT training actually is, and is there a way for people listening or watching to be able to differentiate between the different types or forms that they may see out there?

• HIIT definitely has a bit of a brand issue, says Peter
• Part of the problem with everything we’re about to discuss today stems from the fact that there’s no uniform definition in what constitutes HIIT
• Peter suggests that we be a little bit more specific and we differentiate between, for example, high-intensity interval training, or HIIT, versus sprint interval training, or SIT, or things like Tabata training (which kind of are a bit of a subset of SIT)
• The reason for that is they produce very different metabolic effects, they’re carried out at very different intensities, and by extension, they have different pros and cons

{end of show notes preview}