Long run · Saturday, 19 September 2026 · Week 4, Durability Base
Long run, 12.1 miles
27 weeks to MDS
My write-up for this run isn't up yet. Everything the watch recorded is below.
- Distance
- 12.1 mi
- 19.4 km
- Moving time
- 2h 42m
- started 09:24
- Average pace
- 13:28
- per mile
- Heart rate
- 125
- average · max 149
- Climb
- 781 ft
- 238 m
- Conditions
- 19°C
- 81% humidity · wind 25 km/h
The planned long run, done as planned.
Heart rate against my cap
My easy running has a heart rate ceiling of 126 bpm. It keeps the effort aerobic while my legs, tendons and joints catch up with the mileage. A run counts as over the cap when the average is more than 2 beats over it, or more than a fifth of the time sits above it.
Over the cap. Average 125 bpm, with 43% of the run above 126. The fix is to slow down, walk the steeper bits if I need to, and let it settle.
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 1%. Under 5% is what I call held. That band is a coaching convention, not a validated threshold.
Late on, pace slowed 5.5% and heart rate fell 4.5%.
Confidence: medium (the hill correction changed this reading by about 7 points, and it is an estimate).
First half against second half
Comparing pace against heart rate in the first half with the second, the gap was 0.5%. 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 | 12:21 | 122 | 89 ft |
| 2 | 12:47 | 127 | 13 ft |
| 3 | 14:52 | 126 | 128 ft |
| 4 | 13:57 | 127 | 95 ft |
| 5 | 13:28 | 128 | 46 ft |
| 6 | 12:47 | 124 | 7 ft |
| 7 | 14:12 | 124 | 128 ft |
| 8 | 13:19 | 128 | 52 ft |
| 9 | 13:14 | 120 | 52 ft |
| 10 | 15:05 | 119 | 108 ft |
| 11 | 12:34 | 125 | 7 ft |
| 12 | 13:12 | 126 | 13 ft |
Heart rate in orange is above the 126 bpm cap.
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.