Sasha Pachev wrote:
10:10 on a 3 K cross-country course is not consistent with 38:39 10 K and 1:21:21 half. Bolder Boulder is a slow course, but not that slow. I have had several friends (31-34 minute range) run "normal" times there, a bit slower that what they would have on a flat course at the same elevation - maybe 30 seconds or so slower. So with that in mind, she is holding the pace very well from 10 K to the half. But 10:10 on a correctly measured cross-country course at 7000 feet would indicate a very sharp drop in endurance from 3 K to 10 K, which just does not happen for a runner that holds it so well from 10 K to the half.
I do have some good data for that - here in Provo we have a series of cross-country meets where both kids and parents can participate. So I ran a good number of 3 Ks. The course is at about 4500 feet, has some hills that are mild by cross-country standards. On that course I was able to run 10:30 on faster days and 10:45 on slower days. Around the same time I ran a certified Bolder-Boulder like course (maybe even nastier) - Layton Classic - in 36:58. I also was able to hit 35:20 10 K en route to a 1:16:22 half (Monumental in Indianapolis, low elevation, loop course, mostly flat).
Grace Ping ran 14:12 on the 4 K course in the same park along mostly the same route. On that same day I ran 18:29 in the adult section in the 5 K again on mostly the same route. So maybe I would have run around 14:35 in the 4 K. Then Grace ran 16:36 in the 5 K in California on Thanksgiving for another data point. So I would anticipate her to run around 36:00 in Bolder Boulder.
Good analysis, but I didn't mean to suggest these as equivalent times. I was looking through the Denver Rock and Roll half results, and her age and time really stuck out so I did a quick search and found these other results. I'm sure there are plenty of others. Remember, the 3k was at 7000' and with no competition.
Notably, she went through 10k at 38:20 en route to her 1:21 half. Her 5k split was crazy too. Just makes me feel slow how fast these kids are running.