Long run · Saturday, 24 October 2026 · Week 9, Durability Base
Average sits on the cap, with long stretches running hot
22 weeks to MDS
Sixteen miles, humid again, the long run for week nine done but a little different from what was asked. The average heart rate landed exactly on the cap, which sounds fine until you look closer: thirty eight per cent of this run sat above it.
The pace fell away late, 13:32 for the first mile to 15:01 for the last, heart rate climbing from 128 to 137 over the same stretch. The efficiency numbers still sit in the band I call held, under five per cent fade, and the two halves stayed close enough on pace against heart rate. So the engine looks fine on paper. It is the time spent over the cap that I want to watch over the next few long runs.
- Distance
- 16.1 mi
- 25.9 km
- Moving time
- 3h 46m
- started 07:57
- Average pace
- 14:02
- per mile
- Heart rate
- 131
- average · max 154
- Climb
- 433 ft
- 132 m
- Conditions
- 8°C
- 88% humidity · wind 13 km/h
Planned run, distance changed on the day.
Heart rate against my cap
My easy running has a heart rate ceiling of 131 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 131 bpm, with 38% of the run above 131. 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 4.4%. Under 5% is what I call held. That band is a coaching convention, not a validated threshold.
Late on, pace quickened 0.2% and heart rate rose 4.8%.
First half against second half
Comparing pace against heart rate in the first half with the second, the gap was 6%. 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 | 13:32 | 128 | 39 ft |
| 2 | 14:13 | 127 | 7 ft |
| 3 | 14:30 | 130 | 7 ft |
| 4 | 14:13 | 131 | 7 ft |
| 5 | 13:34 | 129 | 0 ft |
| 6 | 13:59 | 129 | 0 ft |
| 7 | 13:53 | 126 | 0 ft |
| 8 | 14:03 | 118 | 13 ft |
| 9 | 13:32 | 133 | 7 ft |
| 10 | 13:59 | 134 | 13 ft |
| 11 | 14:12 | 131 | 7 ft |
| 12 | 14:02 | 135 | 13 ft |
| 13 | 13:20 | 133 | 0 ft |
| 14 | 14:24 | 133 | 0 ft |
| 15 | 14:32 | 131 | 0 ft |
| 16 | 15:01 | 137 | 102 ft |
Heart rate in orange is above the 131 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.