[vsareto]

I thought they present it as ratios as well, so 1:1 is 1 minute on, 1 minute off, or 2m on, 2m off. They give different ratios depending on your level of conditioning, so like 2:1 for fit folks or 1:2 if you're not as fit. I've heard max effort most of the time, but some others have just recommended doing what feels comfortable for newer folks.

[conistonwater]

I got it from searching on google scholar, there were lots of papers on it because it's both a buzzword and a seemingly effective training technique for even high-level athletes. The basic issue with the whole concept is that it's supposed to produce similar improvements to long steady sessions of cardio, but only very hard efforts with short intervals produce such improvements. So beginners can't really do hard efforts very well, and if they also use long rest periods, and especially if they don't go all-out, then the benefits aren't there for them at all and it just becomes false advertising. I think it's a little sad how a valuable bit of sports science got mangled. If you do all this stuff to save time and you don't even get the benefits, then doing low-intensity cardio is just so much better. I run a lot these days but I can't imagine an all-out anaerobic sprint that's 2m long, it seems both difficult and biologically impossible, I think that's just regular interval training (not high-intensity).