Ironman Training Diary - May 19, 2026

On yesterday’s 30 minute run I fell back into my old ways and ran too fast, spending 85% of the run in Z4. Prior analyses indicated my strides were shorter than they should be on the slow runs and so I actively worked on trying to increase stride length. In doing so my pace was too fast from the outset and although I slowed down throughout the run (see below table), I was unable to recover back to the desired Z2 level.

Quarter	Pace
Q1 (0–7.5 min)	10:07/mi
Q2 (7.5–15 min)	12:31/mi
Q3 (15–22.5 min)	11:54/mi
Q4 (22.5–30 min)	12:32/mi

As is typical in Ohio we went from being wrapped in blankets to sweltering heat in the span of about 4 days. It was pushing 90 on the run but I didn’t mind one bit.

My highlight of the day was receiving an email from somebody who is also training for an Ironman (a full)! He found me on https://kagi.com/smallweb/. We’ve already traded a few messages. He suggested watching this YouTube video https://www.youtube.com/watch?v=uL2UY1NesNQ regarding wetsuits, and also mentioned https://www.irontriapp.com/.

Apollo Analysis of May 18 Run

🤖 Apollo (AI) analysis

Metric	Value
Distance	2.63 mi
Duration	30:00
Pace	11:23/mi
Avg HR	163
Max HR	175
Cadence	157 spm
Z4 time	85%

HR drift: first 5 min 135 bpm → last 5 min 172 bpm (+37 bpm)

Honest read

You backed away from what was working. Here’s the last three runs side-by-side:

	May 14	May 16	May 18
Pace	13:12	13:09	11:23
Avg HR	149	161	163
Z4 %	45%	81%*	85%

_{May 16 was 80 min so Z4 time accumulates; per-minute intensity was lower.}

Yesterday was 1:45/mi faster than your two prior runs at almost the same effort cost as the 80-minute long run. The aerobic discipline of May 14 and 16 is gone — this is the old pattern.

The HR drift tells the full story: you started genuinely aerobic (135 bpm) and ended in solid Z4 territory (172 bpm) on a 30-minute run. That’s a sign of pace too high to be aerobic for your current base.

This isn’t a failure run — it’s a normal day in the build. But two breakthrough sessions doesn’t mean you’ve rebuilt your engine; it means you found the protocol. You have to repeat it. Pace temptation creeps back when the run feels “too slow.”

Fix for the next three runs: lock pace to 13:00+/mi, even if it feels embarrassingly slow. Avg HR target under 155. The drift window will widen and the body will lock the adaptation in.

On tomorrow’s 30 minute run I’ll do my best to dial back the jets!

Apollo Analysis of May 19 Run

🤖 Apollo (AI) analysis

Metric	Value
Distance	2.31 mi
Duration	30:00
Pace	12:59/mi
Avg HR	154
Max HR	169
Cadence	156 spm
Z4 time	58%

HR drift: first 5 min 126 bpm → last 5 min 165 bpm (+39 bpm)

Course-correction in progress

Meaningful step back toward the protocol after yesterday’s slip:

	May 14	May 16	May 18	May 19
Pace	13:12	13:09	11:23	12:59
Avg HR	149	161	163	154
Z4 %	45%	81%*	85%	58%

_{May 16 was 80 min so Z4 time accumulates; per-minute intensity was lower.}

Z4 dropped 27 percentage points overnight. Avg HR fell 9 bpm. Pace eased 1:36/mi. You heard yesterday’s feedback and pushed back the other direction.

The standout detail: the first 5 minutes were textbook. You started at 14:03/mi and HR sat at 126 — real Zone 2, the kind of opening you’ve never had before in this dataset. That alone is the most important data point of the week.

Then Q2 happened:

Quarter	Pace	Avg HR
Q1 (0–7.5 min)	13:33/mi	132
Q2 (7.5–15 min)	12:42/mi	155
Q3 (15–22.5 min)	12:58/mi	160
Q4 (22.5–30 min)	13:03/mi	165

You sped up by 51 seconds/mile in Q2 — almost certainly because the slow start felt unnatural. HR jumped 23 bpm in response and never came back down. Q3 and Q4 you held pace steady, but you’d already pushed the system past aerobic, and HR just kept drifting up.

The pattern is now clear: your aerobic base can hold up at 13:00+/mi pace, but the moment you dip under 13:00, you’re paying threshold prices for an “easy” effort.

Next session goal: start at 14:00/mi and stay there for the entire first 10 minutes. Don’t speed up at any point. If you nail that, the rest of the run will take care of itself. The first 5 minutes today proved you can do it — extend that window.

VO2 max still 39.0 — no movement yet, but you’ve only had one truly aerobic week. The body is listening; give it more reps.

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