I'm still confused about this 'muscle strength' thing translating into terms like "Yes he carried a lot of muscle mass into the event but it is most likely that muscle mass which gave him the strength to hold it all together on the day and not end up doing the slow Ironman shuffle while crying into his Gatorade from mile 10."

As far as I understand, the ability to go ironman-long and slow is almost entirely a feature of endurance. Having bulky muscles, even a little bit of bulk, is detrimental to that.

I've heard coaches throwing around the concepts of strength training so you can 'last the distance' at racing such as IM, but aside from a last-second burst of speed, I'm not understanding how all that short-rep strength and muscle bulk does anything whatsoever for the IM endgame shuffle.

(I understand how it would be super helpful for the end sprints in short or even long tris - just watching the Brownlees get smoked beyond belief in a track sprint on that old TV show by the boxer was enough proof of that!)