Intervalsconfidence 0.83
4 × 1km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 1km
Distance
10.0 km
Moving
42:33
Rep pace
3:53/km
Avg HR
164 bpm
Reps
4
Shape of the sessionEasyWorkFastest
warm up
0:004 × work / float42:33
The decode
A four-rep 1km interval set was a defined change-of-pace session. The 6 km before the work made the faster block a test of pace under accumulated load.
The set peaked on rep two at 3:46/km, then slowed on both remaining reps. Heart rate reached 177 on the final rep, up from 170 on the first.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 4:03 | 4:03/km | 170 | — |
| 2 | 3:46 | 3:46/km | 166 | — |
| 3 | 3:49 | 3:49/km | 175 | — |
| 4 | 3:55 | 3:55/km | 177 | — |
0.83
confidence
What the engine saw
- 4 work intervals detected from lap markers, confirmed by clear pace separation.
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
Endurance6%
Z3
Tempo42%
Z4
Threshold36%
Z5
VO₂max15%
Pace
Z1
Easy6%
Z2
Endurance66%
Z3
Tempo20%
Z4
Threshold5%
Z5
VO₂max3%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance2%
Z3
Tempo49%
Z4
Threshold38%
Z5
VO₂max10%
Z6
Anaerobic2%
Z7
Neuro0%
Aerobic decoupling · Pa:HR-5%
Effort & efficiency
0.72
Running effectiveness
speed per watt/kg, reps
6.0 w/kg
Power-to-weight
rep average
2.65
Efficiency factor
norm. power per bpm
1.02
Variability index
1.0 = perfectly even power
2.8%
Rep consistency
pace spread across reps, lower is tighter
1095 kJ
Total work
mechanical energy
689 kcal
Energy
estimated burn
701 bpk
Cardiac cost
heartbeats per km
51%
Above threshold
≥ 164 bpm (Z4+)
-0:30/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace19°C · +44 m
Actual
3:53/km
Grade-adjusted
3:53/km
Heat-adjusted
3:49/km
−4s/km
True effort
3:49/km
−4s/km
The rep pace re-expressed for flat ground and cool air, the effort, not the clock. Adjustments are modest on this one; on a hot day or a hilly route this is where the real work hides.