Long run · Sunday, 9 August 2026

Long run, 13.2 miles

33 weeks to MDS

My write-up for this run isn't up yet. Everything the watch recorded is below.

Distance: 13.2 mi; 21.3 km
Moving time: 2h 52m; started 06:41
Average pace: 13:01; per mile
Heart rate: 124; average · max 145
Climb: 945 ft; 288 m
Conditions: –; 59% humidity

How well the running held up

I compare how efficiently I was running early in the run (speed for each heartbeat, corrected for hills) with the late part. The drop was 4.4%. Under 5% is what I call held. That band is a coaching convention, not a validated threshold.

A sustained drop began around 2h 16m into the run.

Late on, pace slowed 2.5% and heart rate rose 1.9%.

Efficiency across the run against the early baseline (100%). The dashed line is 95%.

First half against second half

Comparing pace against heart rate in the first half with the second, the gap was 5.1%. Under 5% is the convention I coach to: it suggests the aerobic side coped with the length of the run. It says nothing about why.

Mile by mile

Mile	Pace	Avg HR	Climb
1	12:38	116	95 ft
2	12:17	119	13 ft
3	14:16	123	128 ft
4	13:27	123	89 ft
5	12:24	124	39 ft
6	11:44	122	13 ft
7	14:11	123	128 ft
8	12:59	123	46 ft
9	12:25	124	59 ft
10	13:17	127	79 ft
11	14:01	126	115 ft
12	13:13	125	46 ft
13	12:32	122	26 ft
0.26	13:10	134	16 ft

Figures from my watch via Intervals.icu, read by the Ultra Event Training app. Heart rate from a watch is a proxy for effort, not a lab measure. The efficiency figures compare speed per heartbeat early and late in a run with a hill correction; they show what changed, not the cause.