[makeitdouble]

I am aware of that for exercising, but was ignorant of what "intense" actually means in this context. And you're right.

Looking around, the simplest wording I get:

> the intensity must be high. This means that you need to really exert yourself so you get out of breath. [https://norwegianscitechnews.com/2026/05/exercise-a-very-lit...]

So if climbing the stairs gets someone out of breath it's intense (and I also see how getting to your limits, whatever they are, can help)

[adam_arthur]

Yeah, typically "intense exercise" is implying HIIT style cardio.

More and more studies have been indicating that even just a few minutes of intense exercise can outperform long/slow LISS type cardios.

E.g. 5m all out effort is probably better, or at least equivalent, for health than a 30m moderate effort.

The average person can likely hit the 80/20 benefit threshold at less than 30m/week.

[bluecalm]

HIIT vs LISS is a false dichotomy. If you look at endurance athletes the most important part of the training is in "heavy domain" that is between what typical LISS and HIIT are. This is intensity high enough that you need to breathe faster but it's still sustainable for at least 40-70 minutes.

>>E.g. 5m all out effort is probably better, or at least equivalent, for health than a 30m moderate effort.

This is very unlikely to be true. Studies I've seen usually compare low intensity to HIIT and then measure things like VO2max improvements instead of direct health outcomes. VO2max is a good health indicator for general population and it's maximized short term by HIIT style of training but it's not enough to conclude short term improvements in VO2max imply long term health.

>>The average person can likely hit the 80/20 benefit threshold at less than 30m/week.

I very much doubt it. Usual number mentioned is at least 5 hours but in general the more the better.

[adam_arthur]

A 40-70m sustained effort is effectively LISS from a study perspective. The main distinction being made is intensity, and it's impossible to sustain even a marginally intense effort for 40m (unless you redefine "intense" as different from what most studies use)

Recent studies have shown compelling evidence that LISS promotes arterial plaque buildup, while HIIT does not have this effect and has even been shown to reverse it if other parameters are in order.

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.119.0...

"""

Physical activity and exercise training are effective strategies for reducing the risk of cardiovascular events, but multiple studies have reported an increased prevalence of coronary atherosclerosis, usually measured as coronary artery calcification, among athletes who are middle-aged and older. Our review of the medical literature demonstrates that the prevalence of coronary artery calcification and atherosclerotic plaques, which are strong predictors for future cardiovascular morbidity and mortality, was higher in athletes compared with controls, and was higher in the most active athletes compared with less active athletes.

"""

While the health benefits of LISS seem to outweigh this factor, the new evidence that comes out in various studies continually nudge health impact of HIIT over LISS.

I find it difficult to recommend a form of cardio that 1) promotes arterial plaque over one that reverses it, and 2) seems to produce equivalent or worse biomarkers along almost every axis per unit of time spent.

(Not just V02 max)

[Swizec]

> More and more studies have been indicating that even just a few minutes of intense exercise can outperform long/slow LISS type cardios.

For best results run fast and far. During my personal best marathon (3h 15min) my heart rate averaged in the 170 range

[Earw0rm]

How old were you at the time? Mid 40s here and can comfortably sustain low 150s, but burn out quick past 160.

[Swizec]

Mid 30s

[econ]

There (for example) is High intensity interval training.

What that is depends somewhat on who you ask but to give an example.

Take a normal exercise like cycling for 45 minutes.

If you do HIIT you cycle as fast as you can for 10-15 seconds (or until properly worn out) then rest long enough to be able to do it again. You only end up working out for less than one minute or just half a minute in total but you get similar if not better results than the 45 minutes workout.

So yes, running up the stairs as fast as you can until you feel like you are going to die would be high intensity. Take the elevator back down or you might die for real.

[bluecalm]

>>If you do HIIT you cycle as fast as you can for 10-15 seconds (or until properly worn out) then rest long enough to be able to do it again. You only end up working out for less than one minute or just half a minute in total but you get similar if not better results than the 45 minutes workout.

You will improve things like muscle buffer capacity and maybe VO2max (although for that longer intervals are much better) but those are not the most important things for metabolic health or health in general.

Recommending sprinting to untrained people is just a very bad idea. Fatigue and injury risk is higher. Benefits when it comes to metabolic health are lower.

It's important for exercise to be in heavy domain. Maybe it's a good idea to be in severe domain for a while (VO2max training) but typical HIIT hacks maximize pain/injury risk/recovery time while giving less benefits (unless you compare it to something silly like strolling for 30 minutes).