Polarized training

Polarized training is a training intensity distribution where approximately 80% of training time is in zone 1–2 (easy, below the first lactate threshold) and 20% is very hard (VO2max or above), with little or no time in the middle zones. Popularized by sport scientist Dr. Stephen Seiler at the University of Agder in Norway.

Seiler's research on elite endurance athletes across multiple sports showed the 80/20 distribution was remarkably consistent at the top — despite athletes intuitively feeling they should train more in the middle. The 'threshold trap' is the idea that too much time in zone 3–4 produces high fatigue for modest adaptation.

Polarized is often contrasted with pyramidal (a smoother distribution with more zone 3) and sweet-spot-heavy approaches. The best distribution depends on phase: more pyramidal / sweet-spot in base, more polarized as the goal approaches.