I took that marathon failure personally… So this morning, I drove back to the course and started running in the dark by myself. And I got it done: - Final Time: 2:48:47 - Average Pace: 6:26 No, it doesn’t “count” but when I say I’m going to do something, I do it. Full stop.
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Here were the full stats and splits from the run. It was beautiful out (low 50s and low humidity). Despite some fatigue in the legs from last week, I was able to run a nice negative split. Something like 1:25:15 / 1:23:30 for first and second half.
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Most interesting learning: The impact of temperature and humidity on performance is dramatic. Same course with same fitness one week apart. 70 and 90% humidity last week vs 50 and no humidity yesterday. Mile 21: - Hot: 6:42 pace at HR 182 - Cool: 6:14 pace at HR 170 Crazy.

Sep 20, 2026 · 11:21 AM UTC

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Ok, I guess I have to make it official. See you in Indy on November 7th. Special thank you to @JohnGoldman for the bib and @HankFrank for the assist.
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Sort replies: Relevant Recent Liked
Replying to @SahilBloom
Humidity is the performance killer If the dew point is over 65, I know I won’t PR. If it’s over 70, I hope to just be able to finish the race at all
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Replying to @SahilBloom
This also makes it very clear (biologically) why you stopped. It was either that or slow down dramatically. Better to live for another day.
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My mouth got so dry from lack of fluids that I spat blood. That helped make the decision too lol!
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Replying to @SahilBloom
This tracks with my experience. I've done long runs in Gulf summer heat where HR runs 15-20 beats higher at the same pace. Heat is basically altitude without the fitness benefit.
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Replying to @SahilBloom
How many times do you intend to run per week?
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Replying to @SahilBloom
Climate and humidity plays an important role on how the body performs. Strong one considering you ran both halves with same pace and effort- almost 👌💪
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Replying to @SahilBloom
Congratulations- how did you set up fluids and fuel for this?
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Parked my truck alongside the course. It was 10 loops of a 2.62 mile loop. Put bottles and gels on truck bed to grab while I ran by. Only probably drank about 16oz for full race though given good conditions.
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Replying to @SahilBloom
the body is reporting terrain, not character. identical effort can produce a different result when the map leaves out the weather.
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Replying to @SahilBloom
Claude has become my run coach and the analysis of dew point, temp, etc. against pace and heart rate has been fascinating…
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Replying to @SahilBloom
People call weather (or every other factor) an excuse until they see the data.
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Replying to @SahilBloom
This is why pace alone is such a misleading way to compare runs. Same athlete. Same course. Nearly half a minute per mile slower, at a much higher heart rate.
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Replying to @SahilBloom
Performance plateaus are often environment, not fitness — humidity and heat can rewrite pace and heart rate on the same course a week later.
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Replying to @SahilBloom
As a runner in Houston, its incredible--we are entering a time of year when humidity rapidly drops, and you gain speed every week. If you understand how dew point works (water can't evaporate off the skin, body can't cool), it makes sense--I think that's the key number to track
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