4 major zones being Aerobic Conditioning, Anaerobic Conditioning, Aerobic Capacity, Anaerobic Capacity.
The Coe/Martin book of the early 90s famously detailed the parameters of these various types of sessions, and gave sample distributions of said sessions over the various cycles (although much debate ensued as to wether Coe himself adhered to these parameters.)
The Moroccans and others claimed to have been greatly influenced by these ideas.
But that was 20 years ago, and detailed analysis of the training of the greats (El G, Geb), as well as recent insights into USA resurgence, indicates that training within the specific parameters / distributions of the Subj Zones is no longer a priority for many at the top of the world.
Discuss.