Intervalsconfidence 0.83
4 × 2km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 2km
Distance
13.3 km
Moving
55:45
Rep pace
3:42/km
Avg HR
163 bpm
Reps
8
Planned vs actual · TrainingPeaksPlanned 52:54 · 12.0 kmRan 55:45 · 13.3 kmIF 1.41TSS 185
Shape of the sessionEasyWorkFastest
warm up
cool down
0:008 × work / float55:45
The decode
This was a four-by-2km interval set, with 60-second static recoveries between repeats, prescribed to be run consistently hard.
The 2km blocks ran 7:20, 7:23, 7:31 and 7:21, with heart rate rising from 170 to 177. The third block was the slowest; the final block returned to 7:21.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 3:39 | 3:39/km | 170 | — |
| 2 | 3:41 | 3:41/km | 175 | 1:00 |
| 3 | 3:40 | 3:40/km | 175 | — |
| 4 | 3:42 | 3:42/km | 179 | 1:00 |
| 5 | 3:44 | 3:44/km | 175 | — |
| 6 | 3:47 | 3:47/km | 180 | 1:00 |
| 7 | 3:42 | 3:42/km | 177 | — |
| 8 | 3:38 | 3:38/km | 182 | 1:00 |
0.83
confidence
What the engine saw
- 8 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 60s.
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
Recovery16%
Z2
Endurance22%
Z3
Tempo7%
Z4
Threshold16%
Z5
VO₂max39%
Pace
Z1
Easy41%
Z2
Endurance9%
Z3
Tempo38%
Z4
Threshold12%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance7%
Z3
Tempo33%
Z4
Threshold55%
Z5
VO₂max5%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+3.2%
Effort & efficiency
0.76
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
1.1%
Rep consistency
pace spread across reps, lower is tighter
1509 kJ
Total work
mechanical energy
936 kcal
Energy
estimated burn
719 bpk
Cardiac cost
heartbeats per km
55%
Above threshold
≥ 164 bpm (Z4+)
-0:34/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace31°C · +64 m
Actual
3:42/km
Grade-adjusted
3:42/km
Heat-adjusted
3:28/km
−14s/km
True effort
3:28/km
−14s/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.