Intervalsconfidence 0.83
3 × 3.1km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
3 × 3.1km
Distance
15.7 km
Moving
64:47
Rep pace
3:49/km
Avg HR
172 bpm
Reps
3
Planned vs actual · TrainingPeaksPlanned 1:10:00 · 16.5 kmRan 1:04:47 · 15.7 kmIF 1.44TSS 222
Shape of the sessionEasyWorkFastest
warm up
cool down
0:003 × work / float64:47
The decode
This was a threshold set of three 12-minute reps with float recoveries, structured to limit changes of pace and keep the effort controlled. The session was intended to stay below 3/10 pain.
The reps ran at 3:50/km, 3:48/km and 3:49/km, while HR rose from 174 to 180 to 181. The float recoveries quickened from 4:24/km to 4:18/km to 4:16/km, and the pace held together despite the higher HR associated with returning from a cold and 25 C conditions.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 12:00 | 3:50/km | 174 | 3:00 |
| 2 | 12:00 | 3:48/km | 180 | 3:00 |
| 3 | 12:00 | 3:49/km | 181 | 3:00 |
0.83
confidence
What the engine saw
- 3 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 180s.
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
Recovery4%
Z2
Endurance10%
Z3
Tempo1%
Z4
Threshold24%
Z5
VO₂max60%
Pace
Z1
Easy16%
Z2
Endurance30%
Z3
Tempo53%
Z4
Threshold1%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance5%
Z3
Tempo32%
Z4
Threshold52%
Z5
VO₂max10%
Z6
Anaerobic1%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+1.9%
Effort & efficiency
0.72
Running effectiveness
speed per watt/kg, reps
6.0 w/kg
Power-to-weight
rep average
2.54
Efficiency factor
norm. power per bpm
1.02
Variability index
1.0 = perfectly even power
0.5%
Rep consistency
pace spread across reps, lower is tighter
1755 kJ
Total work
mechanical energy
1117 kcal
Energy
estimated burn
747 bpk
Cardiac cost
heartbeats per km
84%
Above threshold
≥ 164 bpm (Z4+)
-0:11/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace25°C · +43 m
Actual
3:49/km
Grade-adjusted
3:49/km
Heat-adjusted
3:40/km
−9s/km
True effort
3:40/km
−9s/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.