Raceconfidence 0.80
HBF Half Marathon
Colin Dismuke50 km / marathon build
Source: own Strava export
Race
HBF Half Marathon
Distance
21.3 km
Moving
88:03
Avg HR
186 bpm
Shape of the sessionEasyWorkFastest
0:00session88:03
The decode
This was a 21.26 km race in 1:28:03 at 4:08/km. It demanded a progressive opening followed by sustained pressure, but the pace did not hold through the closing section.
The opening full-kilometre laps tightened from 4:00/km to 3:55/km as HR rose from 165 to 193. The pace then broke to 4:11/km, briefly returned to 4:02/km, and drifted to 4:32/km late while HR stayed between 184 and 190; the session maximum was 195.
0.80
confidence
What the engine saw
- Raced 21.3 km at 186 bpm avg, even pacing held under pressure (CV 5%).
- Matches the athlete's own session label.
Calibration flags
- Running power threshold estimated from the athlete's half-marathon best efforts (60-min power 476 W, 95% of 20-min power 460 W). Treat power zones and load as ±3%.
- Zones and running threshold are one snapshot, read 2 Jul 2026 and applied to every session in the archive. An older session is scored against today's zones, not the zones the athlete trained with then.
Engine read · editorial decode by Splits
Time in zone
Heart rate
Z1
Recovery1%
Z2
Endurance0%
Z3
Tempo0%
Z4
Threshold4%
Z5
VO₂max95%
Pace
Z1
Easy0%
Z2
Endurance50%
Z3
Tempo50%
Z4
Threshold0%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance2%
Z3
Tempo27%
Z4
Threshold55%
Z5
VO₂max15%
Z6
Anaerobic1%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+7%
Effort & efficiency
0.70
Running effectiveness
speed per watt/kg, reps
5.8 w/kg
Power-to-weight
rep average
2.39
Efficiency factor
norm. power per bpm
1.02
Variability index
1.0 = perfectly even power
5.2%
Rep consistency
pace spread across reps, lower is tighter
2330 kJ
Total work
mechanical energy
1531 kcal
Energy
estimated burn
774 bpk
Cardiac cost
heartbeats per km
99%
Above threshold
≥ 164 bpm (Z4+)
+0:20/km
Split balance
positive split, slower 2nd half
Conditions-adjusted pace21°C · +65 m
Actual
4:08/km
Grade-adjusted
4:08/km
Heat-adjusted
4:03/km
−5s/km
True effort
4:03/km
−5s/km
The rep pace re-expressed for flat ground and cool air, the effort, not the clock. The gap between actual and true effort is the day's hidden work: conditions were taxing the clock.