Esteve-Lanao et al. 2007, Impact of training intensity distribution

With hard intensity equalised between groups, the runners who did more easy volume — a polarised distribution of roughly 80% easy, 12% moderate and 8% hard — improved their 10.4 km time more than a less-polarised threshold split (67% / 25% / 8%). A canonical experimental result for polarised, not pyramidal, training. Moderate.