I think many people who suggest that they follow a Lydiard system are really like those who subscribe to Darwinism. They don't follow the original teachings exactly but rather the advancements that have been made on those teachings but keep the name. Darwin was brilliant but the neo-darwinian synthesis and recent genetic findings have altered our view of how evolution works but some of the general principles espoused are what we hold onto and refer to without looking at the nitty-gritty.

I think Lydiard was the first person to demonstrate success by having athletes (and not just runners) develop a huge aerobic base. That is the part most people remember and think of Lydiard the icon. He once (maybe many times) said that all runners can benefit from marathon training. The only book of his I have is "running to the top" (it's not very good compared to modern books but that is the point of this blog now isn't it). In it, he says, "If you want to do a lot of training or exercise to improve your physical condition without building up waste product, the effort has got to be aerobic." This is under the heading: "Training and not straining." He also railed against modern footwear being the cause of many running injuries. He describes Long Aerobic Running as, "A strong aerobic effort, between jogging and racing - in theory, 70% to 99% of your aerobic capacity to finish in a pleasantly tired state." I think you're right in that now my belief is that it should generally be easier than he suggests to get the benefits of aerobic training without the stress that fatigues your legs and thereby prevents more mileage or adequate workouts.

As for the nuts and bolts, I think you're right that we've improved and refined training methods. You could argue that is why his most talented athletes (Viren) weren't running faster than guys like Rupp, Adam Goucher, Meb, Ritz, and similar level athletes (i.e. ~13:10, 27:00).

I don't know that 4 weeks of specialized hill training as he suggests (with no hill training later) is the best approach. However, I will play devil's advocate and argue that something like that might be necessary rather than integrating more training variety. You suggest that detraining reduces the utility of a hill phase followed by a complete switch to other types of workouts (tempos and intervals). The counter argument is that you might not be able to successfully get from step A to step C without step B (say hills in this case). Or in a more complicated analogy you ultimately want to get to race at step E. You could go from step A to step C but then from step C you can only get to level D to race. However, if you were to progress through the ideal steps of A followed by B, then C and D, then you could race at E. This is all in theory and in reality training and physical adaptation to stress might not be so stepwise. However, we believe in periodization, at least I do, and stimulus needs to be added in a gently increasing manner, so what is to say that there isn't some optimal stimuli that need to come before others for maximal success? So, using the hill example, maybe running the hills allows for increased strength and efficiency and lactate tolerance without the pounding impact of running fast over flat ground. I don't really think that Lydiard was right in this or how he had the hills performed but there could be something to the theory at least. In reality, I think that we're all so far from our maximal (genetic) potential that getting to that level of detail is an unnecessary distraction (from my PhD) and that a few general principles dominate:

1. Do lots of easy, aerobic mileage

2. Slowly add additional stimuli

3. Diversify the stimuli (either by workout or within workouts)

4. Tempos are important as is event specific workouts (running at race pace)

5. Avoid getting away from mileage and aerobic training for very long because that detraining will definitely be detrimental!

6. Rarely push yourself to run hard when you are tired and after you do you need to recover.

7. Recovery is key to improvement but can generally be done while running slowly if already properly trained (i.e. good aerobic base).

I guess those are my thoughts for now. I hope they make sense. That was a huge brain dump.