Interesting thoughts Brian, thanks for this- saw it right before the race. I ironically sprained my ankle 2 weeks prior and wore a neoprene brace. Makes sense to recover on the downhills, and typically that hr zone map is how I’d do a really long training hike/run. I decided to just go for it, however, and ignore HR completely (kept an eye on average pace targeting sub 7hr). Really enjoyed the first half, particularly opening it up along Headwaters ridge and the decent which I had looked forward to running. I should have descended slower and that bit me in the ass. I hit a wall between miles 8 and 9 at 2.5hrs in (and average hr of 168bpm looking at the data). Suffered through the next couple miles up to Lone Peak, took the descent in a fast walk rather than run, recovered and eventually finished feeling much stronger in 6:41. If I had done the first major descent slower my guess is I would have finished in a similar time and not felt as shitty for an hour. Who knows if the altitude played a bigger factor as well (no recent experience at altitude).
How did it go for you??