Carbonfiberboy 

Yes. Is it possible to train aerobic with almost no anaerobic component? My reading says that PT trained elites produce almost no lactate below AeT, which might indicate that's true? OTOH we can't only train anaerobically, but we can train that metabolic contribution as hard as we can. The question in all this is what's the perfect mix of training? Lots of debate about that. It seems possible that the usual training of varying amounts in the various zones is simply another way of coming at that same problem, but with more history to it - and perhaps less chance of injury by adding in the anaerobic component more gradually, starting with zone 3, etc. It's also interesting that the PT anaerobic training is all relatively low end for that sort of thing, 105% FTP, no more. Whereas the usual zonal training would have us doing 3 X 3, 1 X 1, 30"/15", etc. at much higher proportions of AnT. I don't understand the logic. Perhaps no one does yet - so many studies out there now. But of course human studies are always flawed. So difficult to isolate the variables.