Tempo run this morning. Got decent sleep, went to bed at 11, got up at 6. It was cold, around 35 degrees, but warmer than last winter. No significant wind. Ran the standard 5 mile tempo from Geneva Road to the trail entrance by the Utah Lake Park and back.
First mile, 5:32. Second 5:31 (11:03), then 2:47 for the next 0.5, 13:50 at the turnaround. The pace felt very comfortable, however I knew that any faster would be exceptionally uncomfortable. HR took forever to get going, but finally stabilized at 158 by 1.5 miles.
2:50 for the next 0.5 with the first quarter after 180 turn in 1:26. The first 100 of it was 23 seconds, so 2 second loss. 5:37 for the mile, 16:40 at 3. Next mile in 5:35. HR climbed to 160, and now the pace is starting to feel harder, although it is still the same pace, even a bit slower, but coming back is a very slight uphill, so 3 seconds per mile is about the correct amount of difference. The breathing became harder too. The sour feeling in the quad appeared but I was able to run through it this time.
Quarters for the last mile - 1:25 (uphill), 1:24, 1:23, 1:20. HR maxed out at 169 at the end. Total time 27:47.8, best time for the season. Last mile in 5:32, last 2.5 in 13:57, I would call this a true even split, perhaps even negative if you throw in the 2 seconds lost on the 180 turn.
Did a long cool down, total of 13.1 for the run. Ted did the easy running with me, he was planning on joining me for the tempo, but got sick. Ran with the kids in the afternoon, total of 14.9. I am running the Salt Lake Half, not the full marathon. Will do it completely untapered. It is fun to race a half at the end of a 90 mile week, I've done this before. You hurt from the start, as opposed to from mile 3, so you actually get better pacing.
I was very happy with this tempo, most particularly about being able to hold the pace as the quads start feeling sour.
I am perplexed as to why HR takes so long to get going in a tempo run. It took a good 4 mile stretch before it got to where it was supposed to be. My average HR for the run was actually 153! This has been a pattern regardless of the weather. So here is what I am wondering about. If I am running 5:32 pace, and the HR eventually stabilizes at 162 then if it is let's say 153, and assuming I do not severely dehydrate in 4 miles of tempo running in 35 degrees (reasonable assumption), and the stroke volume does not drop as the tempo run progresses (reasonable assumption?), and the biomechanical efficiency does not change that much (reasonable assumption?), then at 153 HR my cardiac output is significantly lower than what is necessary for a steady state that happens at 162. But the energy for the pace has to come from somewhere, so that in essence means I am running anaerobically for the first 4 miles of this run. Could it be that HR response to lactic acid build up, and unless you have a certain lactic acid concentration, it will not increase?