Intervalsconfidence 0.83
4 × 1km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 1km
Distance
12.6 km
Moving
58:47
Rep pace
4:08/km
Avg HR
144 bpm
Reps
4
Planned vs actual · TrainingPeaksPlanned 6.0 kmRan 58:47 · 12.6 kmIF 1.27TSS 157
Shape of the sessionEasyWorkFastest
warm up
0:004 × work / float58:47
The decode
Four 1 km reps formed a cut-down within a double-run day, demanding restraint early and a committed finish.
The reps progressed from 4:21/km to 3:56/km as heart rate rose from 152 to 168. The set held together as the pace sharpened, while the 169 heart rate in the final 562 m showed the effort remained elevated after the reps.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 4:21 | 4:21/km | 152 | — |
| 2 | 4:11 | 4:11/km | 154 | — |
| 3 | 4:02 | 4:02/km | 165 | — |
| 4 | 3:56 | 3:56/km | 168 | — |
0.83
confidence
What the engine saw
- 4 work intervals detected from lap markers, confirmed by clear pace separation.
- Rep paces descend across the set (a cut-down / progression).
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
Recovery61%
Z2
Endurance16%
Z3
Tempo7%
Z4
Threshold16%
Z5
VO₂max0%
Pace
Z1
Easy61%
Z2
Endurance24%
Z3
Tempo15%
Z4
Threshold0%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery1%
Z2
Endurance21%
Z3
Tempo62%
Z4
Threshold16%
Z5
VO₂max1%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR-3.7%
Effort & efficiency
0.75
Running effectiveness
speed per watt/kg, reps
5.4 w/kg
Power-to-weight
rep average
2.67
Efficiency factor
norm. power per bpm
1.02
Variability index
1.0 = perfectly even power
3.7%
Rep consistency
pace spread across reps, lower is tighter
1338 kJ
Total work
mechanical energy
865 kcal
Energy
estimated burn
674 bpk
Cardiac cost
heartbeats per km
16%
Above threshold
≥ 164 bpm (Z4+)
-0:45/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace23°C · +38 m
Actual
4:07/km
Grade-adjusted
4:07/km
Heat-adjusted
3:59/km
−8s/km
True effort
3:59/km
−8s/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.