Unsuccess

Well, on the heels of Thursday's great tempo, I had a rather disappointing failure of a long run today. The goal was 2:40, but bonked pretty hard around 2 hours and made it only as long as 2:10. This made it almost identical in distance and time to the long run I did on August 18th, except for the end: on the earlier run I never bonked; in fact I felt strong at the end and was pretty sure I could have done another 15-20 minutes without too much difficulty.

Here's a summary of the two runs:

August 18th, successful long run

Distance:         16.78 mi
Time: 2:15:02
Avg Pace:         8:03 min/mi
Elevation Gain: 1,367 ft

split       time                     dist.      pace
1      35:27.1 4.33      8:11
2      57:32.7 7.02      8:12
3      27:01.9 3.44      7:51
4      15:00.0 1.99      7:33

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Weather: Cool, cloudy, intermittent rain, probably in the 60s.
Terrain: Varied, but substantial flat sections along the Charles River. Roughly 2/3rds trail.
Nutrition: 3x shot blocks (i.e. 1/2 package) and water, my usual.


September 1st, unsuccessful long run

Distance:         16.88 mi
Time: 2:10:01
Avg Pace:         7:42 min/mi
Elevation Gain: 690 ft

split     time               dist.     pace

1    1:00:07.8 7.77    7:44
2    59:53.6 7.89    7:35
3    9:59.4 1.21    8:14  *bonk*

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Weather: felt like 70s, sunny, with a cool breeze.
Terrain: 100% road; mostly rolling hills (I'm shocked this route had less elevation gain than the other)
Nutrition: 3x shot blocks and water, +1 salt tab.


So why the big difference? Let's see...
Nutrition: pretty much identical. I know some would suggest eating more, but I honestly don't think that's it.
Terrain: The lengthy trail sections probably helped save my legs, but I'm unsure how much.
Weather: Today's weather felt gorgeous. But I think it might have been easy to underestimate the affect of the sun, which is still quite potent. Likely contributing factor.
Pace: yeah...I'm dreading that this is the main factor. The 30s /mile difference, stacked over 12-13 miles, is perhaps wearing me down?

I have two more long runs scheduled. I have been running with my Garmin showing only chrono, because I didn't want to get distracted by pace, but I think next time I'm going to reverse that and forceably limit myself to 8 minute miles. Discouraging--it almost feels like the long tempos are pointless, since they don't seem to make a whit of difference in when I crack--but for now I guess I'm just going to try to keep the optimism that somehow endurance and speed are going to come together in time for the race.

(Feeling pretty sore now, but I'm signed up for Walpole 10K on Monday. We'll see how it goes).