alt Hacker NewsHIIT 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.
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...
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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.
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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)