I'm in China at the moment, and one hour ago I went in LR for the first time in the last three weeks. When I read the title of this thread, I was interested, since we have Always something to learn, and I went to read every post.
I found something, in my opinion, right, and something very strange, especially from your side (Jono).
1. How can you say that the first lap of 800m is anaerobic, and the second aerobic ? Due to the accumulation of lactate, which at the end is higher that at the beginning, I really don't understand how it's possible to think "this is something of basic physiology". I think we speak about two different physiologies...
2. You have reason speaking about VO2 max as "natural baggage", of course when a person is mature (about 20-22 years of age). But you can't really think that the strong improvement athletes can have from a situation of "no training" to a situation of "full specific training" is only due to the increase of efficiency and running economy.
The best athlete in the World in Marathon (now Wilson Kipsang) if doesn't run for 1 year preserves the same VO2 max (or loses only a little under this point of view), but is not able running 2 hours at a pace of 3:30 per km, when his WR is at the pace of 2:55.
And Rudisha, with one year without training, can run 1:53, if lucky, probably 1:55 or slower.
So, to think the the metabolic and bioenergetic situation doesn't change with training, but every improvement comes on the biomechanical side only, in my opinion is something impossible, and show little practice in real coaching.
3. And also it's a methodological mistake to put the "anaerobic capacity" before the "anaerobic power".
When we speak about lactic system, we have 3 different situations, also if in many books of methodology we can find 2 levels only :
1. The Lactic Power, that is the ability of the Lactic System to have the higher production of lactate divided per the time of the effort. We can see this with a maximal effort on a distance from 300m till 600m, depending on the type of runners we test. If he hs the characteristics of a 400m runner, his LP reaches the highest level in a time between 30" and 45" (equivalent of a race of 300 - 400m). In the case of an 800m runner, he can reach his highest value in an effort lasting 1:00 - 1:30 (500-600m).
2. The Lactic Capacity, strictly connected with the LP, that is the ability of the Lactic System to produce the higher amount of lactate. This can happen running efforts near the max intensity (for example, 98% of LP) resting bout 8' - 10' in between, for a limited number of times (for example, 3 x 600m). This lactate produces high accumulation in the muscle fibers, and this type of training is necessary in order to increase the TOLERANCE of lactate in the muscles.
3. The Lactic Resistance, strictly connected with the Aerobic Power, that is the ability to remove quickly the lactate in the fibers. There are specific workouts for increasing this ability, that physiologically speaking provoke an increase of the permeability of the membranes.
Methodologically speaking, this can be, for example, 10 x 600m at 90% of LP with more short recovery (2'-3').
In this case, the first tests produce a level of lactate UNDER the Lactic Threshold, but, because the recovery doesn't allow the full elimination of lactate, the final level is higher than the LT : for example, the athlete starts with one test at 3.5 mml, the second is 4.5, and at the end can reach 10-12 mml.
This type of training is, obviously, lactic, but its effect is to enhance the Threshold, and is the key of the balance in the training of 800m.
The most important point to understand is that small differences of speed must be considered DIFFERENT MEANS of training, so we have a stair of speed and the athlete has to use ALL the stairs for building his performance.
It's ridiculous to ask "is it better the aerobic training or interval training", "is it better Lydiard or Daniels", "is it better to use speed or long run".
Training is the right combination of ALL this elements, and under this point of view Lydiard had reasons when answered, about the question "which was the most important training", ALL.