A.M. Ran with Jeff and Mary Ann. Warmed up 1.3. Then paced Mary Ann through a long tempo on the 10 K race course. 6:20 pace to failure or to 30 K. Splits by 5 K:
20:03 - (slow start, we gave her an easy warm-up mile) - 19:47 (lost some time on the bottle pickup) - 19:53 (lost some time on the bottle, Mary Ann still does not know how to drink while running fast, also towards the end she started slowing down to 6:30, so I told her to stop at 15 K and jog back). Afterwards, I picked up the pace. 18:47 (that was all I could do) - 18:38 (figured out how to relax better) - 19:11 (fuel shortage/neural fatigue coming out).
Total time of 1:56:19 for 30 K, 6:14 average.
A couple of observatons. A whole lot of difference in the perceived muscular effort between 6:00 pace and anything faster between 15 K and 25 K. In the last 5 K that threshold moved to around 6:10. That threshold kept fluctuating, and did not always change in the slower direction as the run progressed. It had a lot to do with the art of relaxing.
Also, my first 15 K was done in 59:43, while the second in 56:36. I could not have gone any faster in the second. But I am very certain that if I had run the first one in 56:36, my second one would have been quite a bit faster than 59:43. Very possibly another 56:36.
So from that some ideas. We take a runner and have him race an all out marathon. Give enough time for recovery , and while in the same shape, he run a half 5-10 minutes slower than one half of his marathon time, and then a half all out. We call that "tired half" PR. Now Sasha Science Marathon Pacing theory. A marathon is properly paced when the first half is run at the fastest possible pace that still allows you to be within one minute of the tired half PR in the second half. Of course we assume equal terrain and condition for both halves which is never the case in any Utah marathon except maybe Ogden on a cool day.
This does can often mean a positive split depending on the runner. I suspect for a properly trained athlete the range is from 1 minute negative split to 5 minute positive split. For a less fit runner it could be as much as 10-15 minute positive split.
Afterwards paced Benjamin through a 5 K in 21:31. He took thrid place overall. Jenny won the mile with 8:00, Julia was second in 8:23. Jacob ran the 200 race in 1:34. Joseph did it in 1:22.