Run · Friday, 16 October 2026 · Week 8, Durability Base
An easy run slows late while heart rate barely moves
24 weeks to MDS
Five miles, week eight of the plan, done as planned.
The average came in three under the cap, but a fifth of the time out there ran above it. Oddly, the pace eased off late rather than quickening, 12:44 for the first mile against 13:34 for the last, while heart rate barely shifted, 126 then 125. That is the opposite pattern to recent easy runs, where effort has climbed as pace picked up.
I will watch whether that time above cap keeps turning up on easy days regardless of pace, or whether this one was just an outlier.
- Distance
- 5 mi
- 8.1 km
- Moving time
- 1h 07m
- started 12:34
- Average pace
- 13:16
- per mile
- Heart rate
- 128
- average · max 145
- Climb
- 322 ft
- 98 m
- Conditions
- 13°C
- 68% humidity · wind 15 km/h
Planned easy run, full distance.
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.
Under the cap. Average 128 bpm, with 20% of the run above 131.
Mile by mile
| Mile | Pace | Avg HR | Climb |
|---|---|---|---|
| 1 | 12:44 | 126 | 121 ft |
| 2 | 12:17 | 128 | 13 ft |
| 3 | 14:15 | 132 | 121 ft |
| 4 | 12:53 | 133 | 46 ft |
| 5 | 13:34 | 125 | 13 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.