Yup

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https://www.strava.com/...tes/zachary_mckinney

Cool article. But I quibble with calling the exercise regimen described as "HIIT." It was 4x4:00 with 4:00 rest. That's a pretty standard VO2 interval workout. HIIT generally describes much shorter, much more intense intervals. E.g. 10-20 seconds Tabata-style at the short end, out to maybe a minute at the longer end.

I looked at the abstract because the article didn't specify a number of things.

There was only a trend for the HIIT group to have a reduction in mortality of a percentage point or two compared to the continuous moderate intensity continuous training (MICT) group and the control group (which were to follow the typical exercise for health recommendations, so I presume a fair bit of walking).

Interesting that there was no difference between MICT group and the controls, or between a group that did MICT and HIIT (probably most similar to how most people here train, although at lower volume), only the ones that just did HIIT was there that trend towards a small difference.

IOW, if you're old and doing a fair bit of walking you're probably getting the vast bulk of the mortality reducing benefits of exercise you're going to get. Higher intensities don't appear to do all that much for you at least from a mortality perspective.

I noticed this also.

The questions I always have is:
How do we decide what is "hard"?
How do we decide what is the correct length of time?
How many intervals?
How many times per week?

The answer to these questions seems more obvious when we are thinking about athletes preparing for an event.

But things like official HIIT training is often targeted at average people just trying to stay in shape.

What does it mean to go: "100% for 30 seconds and easy for 30 seconds"???
(When you are unable to do a full hour of aerobic activity. And you haven't done any sprinting since elementary school).

There was some HIIT marketing training plan that said something like:
"All you need to do is 2 workouts per week. With 30 seconds at 100%, and 30 seconds easy."

I actually kind of agree with that. That's totally badass, and really hard.
Consider- I am a 48 year old triathlete that can run a 30 second 200.
Now consider this training philosophy-
"All one has to do is run 12 x 30 second (I.e. 200M), with a 30 second rest in between?????
Twice a week??????
That is ALL the training I need???

Well, sure!!
That's one hell of a workout.
And if I could do that twice a week- I would be super, duper fit.

But how???
How do I get in shape to do that?

Good discussion. We were fortunate to have the lead research scientist involved in the study (Dr. Trine Moholdt) referenced on the Catalyst Health, Wellness & Performance Coaching Podcast right after the study was published. It's episode #144 if you want to access it through your preferred podcast outlet or here's a direct link: https://www.buzzsprout.com/204059/6662456

There's also a video version of the interview available if preferred.

Really? I think of VO2 max efforts -- including intervals as long as maybe 8 minutes -- as part of HIIT. Sweet spot for 20 minutes, no. But 4, 5, maybe 8 minutes as hard as you can? Why not?

Just terminology quibbling. The term "HIIT" started as a way of describing *really* intense efforts. Something close to maximum intensity. Not maximum intensity over a duration, but literally as hard as you can go, which means it can't last a minute, much less 4-8 minutes. This was to differentiate it from what, before, was considered normal high intensity training, e.g. the 4-5 minute efforts we've all been doing forever. But now it's been kind of watered down to also describe what's long been conventional high intensity training.

Not the end of the world, just pointing it out.

Another interesting fact iirc is that Tabata in his original paper, which used something like :10hard/:20ez was trying to find ways to increase anaerobic capacity and actually increased vo2max instead.

I think a lot of reasons why HIIT works for people is it's not well trained endurance athletes. If you look at some of the research that's done on people doing it they are often untrained or lightly trained, do HIIT for 6 weeks and see improvement. Yet most of that improvement is motor unit recruitment, neural drive and not some of the parameters that make endurance athletes successful

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

In my experience the terms for different exercise intensities in the exercise/medical world usually don't correspond all that well with the athlete/training world.