Originally Posted by RChung

Even Seiler, one of the earliest proponents of polarized training, said he came to his polarized recommendations by observing high volume elite national- and Olympic-level athletes; and his 80-20 polarization is about sessions, not about time. That means he was suggesting that 80% of high volume athletes' intention for sessions should be low-intensity sessions, and 20% of training sessions should be intended to be high-intensity (Seiler uses a 3-zone system, so his Z1 includes what most of us call "Zone 2"). He doesn't think that a low-intensity session needs to be low intensity every second, just as he doesn't think high intensity must be high intensity every second. One-third of a Tabata Interval session is low-intensity.