What Really Happens in Ironman?

Question:
What really happens in the IM Marathon?

Reading race reports from various people, once again the common theme of losing significant time on the run appears. It is apparent even w/ people that claim to take the bike "easy" and are veteren IMers. What is the physiological change that occurs? Is it the accumulation of lactate, the depletion of muscluar energy stores (glycogen) or something else? If it is lactate, would not more training near LT help (which is what many people do and does not appear to help).

Trying to put pieces of the puzzle together.

-- Tondo

Answer:
I think a lot of people are JFT (tired). It's a long day out there.

For the run -- the key goal is to create a durable set of legs with outstanding overall aerobic fitness -- from a run point of view...

Gradually, safely, build up your running frequency. This can take many seasons
Address your personal nutritional limiters
Do your long runs in the hills to build all around leg durability and strength
Focus on excellent bike aerobic power and strength endurance (not tempo endurance as many interpret this statement -- I'm talking CP360).
Once you have all that fitness and endurance... don't use it! Save yourself so that you can run the last 10 miles of your race FAST.

I'd say that's the bulk of it -- once you have that rolling then you can creep the overall steady-state running volume up. The next step after that is some faster work but that's pretty elite stuff.

Most athletes are running so far below their existing run fitness that we are really looking to overall endurance (best trained on the bike) and durability (best trained with frequency).

That's the way I see it.

gordo