Run · Wednesday, 16 September 2026 · Week 4, Durability Base
A near-cap average hides a lot of time over it
28 weeks to MDS
The average heart rate looked tidy, one under the cap, but that number was hiding something. Forty two percent of this five mile run was spent above the cap despite that average, on a day with 322 feet of climbing and nothing unusual in the air.
Pace held steady from first mile to last, 12:44 down to 12:39, while heart rate crept up a touch over the same stretch. Nothing here is alarming by itself. I'll be watching whether this gap between average and time over cap turns up again on the next few easy runs, or whether Wednesday was a one off.
- Distance
- 5 mi
- 8.1 km
- Moving time
- 1h 05m
- started 17:01
- Average pace
- 12:56
- per mile
- Heart rate
- 125
- average · max 142
- Climb
- 322 ft
- 98 m
- Conditions
- 16°C
- 64% humidity · wind 17 km/h
Planned easy run, full distance.
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 29% of the run above 126. The fix is to slow down, walk the steeper bits if I need to, and let it settle.
Mile by mile
| Mile | Pace | Avg HR | Climb |
|---|---|---|---|
| 1 | 12:44 | 121 | 121 ft |
| 2 | 12:04 | 126 | 20 ft |
| 3 | 14:10 | 129 | 121 ft |
| 4 | 13:15 | 126 | 46 ft |
| 5 | 12:39 | 125 | 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.