Durabilityby Darren Ware
← The training log

Run · Wednesday, 16 September 2026 · Week 4, Durability Base

Run, 5 miles

28 weeks to MDS

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

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

The planned easy 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.

58% at or under 12642% above

Over the cap. Average 125 bpm, with 42% 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

MilePaceAvg HRClimb
112:44121121 ft
212:0412620 ft
314:10129121 ft
413:1512646 ft
512:3912513 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.