[nostromo]

The whole point of HIT is that you get all of the cardiovascular benefits of endurance sports without the repetitive stress injuries.

And the current evidence is that your maximum exertion is what matters, not time spent exercising. So someone that does a few sprints, to max intensity, over 20 minutes actually will have better cardiovascular health than someone that runs or jogs for an hour or more.

If you’re sprinting at full exertion for a few minutes, you’re able to hit a much higher max than you would if you were running long distance.

[bluntfang]

GP's point is that long distance runners are also doing HIIT if their training is managed properly.

[md2020]

> The whole point of HIT is that you get all of the cardiovascular benefits of endurance sports without the repetitive stress injuries. And the current evidence is that your maximum exertion is what matters, not time spent exercising.

This cannot be true, it contradicts literally all the best training knowledge for distance runners. NCAA cross country coaches and professional distance coaches have their runners doing high mileage easy days and intervals on hard days, and as someone who has experienced this training first hand, you absolutely cannot do the hard days at a proper intensity if you haven’t built up your aerobic capacity through a LOT of easy to medium effort long runs. If they could get all the cardiovascular benefits from HIT, they would only be doing that. The teams that win college championships and the pro teams sending athletes to the Olympics are the ones with the fittest runners, the fittest runners are the ones with the best training. They are doing the majority of their mileage in long easy efforts.

Anecdotally, myself and many teammates I’ve known have seen our biggest jumps in performance come from increasing weekly mileage (more easy miles) and while keeping the volume of hard efforts the same. Time spent exercising matters very much.

[nostromo]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6763680/

> HIIT (high-intensity interval training) and sprint interval training (SIT) for 6-8 wk increase VO2peak more than or at least comparable to MCT (moderate-intensity continuous training).

> The clinical and physiological benefits of HIIT compared with those of MCT are shown in Table Table1.1. In multiple RCTs, a wide range of targets, including skeletal muscles[19-22], risk factors[21], vasculature[19-22], respiration[22,23], autonomic function[24], cardiac function[20,22,25-27], exercise capacity[26], inflammation[27], quality of life[27], physiological markers such as VO2peak, and endothelial function, showed better improvements with HIIT than with MCT.

This is true even though the HIT groups were spending just minutes sprinting a few times a week, vs the MCT groups that spent 30 minutes to an hour running or jogging.

[scruple]

I'd love to see links to this research because it contradicts everything I know and have read regarding physical adaptations in our aerobic and anaerobic systems. Specifically, it is my understanding that you need the minimum effective dose in both to force those adaptations and then maintain them.

[enjeyw]

I'm naive in the space so take this with a grain of salt, but I believe the original Tabata study[0] showed comparable increases in participant VO_2 max compared to non-HIIT, with only a 4 minute workout.

Put that alongside evidence that sustained exercise (how sustained I have no idea) has negative effects (as per above comments), and the argument seems plausible.

[0] https://en.wikipedia.org/wiki/High-intensity_interval_traini...

[scruple]

I am familiar with the original Tabata study. I guess my point here is that it's been widely accepted, at least for the last decade or so (Dr. Maffetone was figuring some of this out in the early 80s, FWIW...), that HIIT (and strength training) cause concentric cardiac hypertrophy, whereas LISS primarily causes eccentric cardiac hypertrophy. I'm speaking very generally here, but... 1 increases the size of your heart, thus the volume of blood and therefore oxygen (it has to pump less to deliver oxygen to your muscles leading to a lower BPM), and the other makes your heart stronger (it can pump all of this extra blood). This is all of course a very unscientific explanation and I'm not an expert.