Intervalsconfidence 0.83
4 × 2km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 2km
Distance
10.0 km
Moving
40:09
Rep pace
3:55/km
Avg HR
154 bpm
Reps
4
Planned vs actual · TrainingPeaksPlanned 54:19 · 12.0 kmRan 40:09 · 10.0 kmIF 1.68TSS 188
Shape of the sessionEasyWorkFastest
cool down
0:004 × work / float40:09
The decode
Four 2km reps made up a cut-down interval set. The recoveries separated the work without breaking the session’s progression.
The first three reps stayed tightly grouped at 3:58/km, 3:57/km and 3:59/km before the final rep moved to 3:45/km. Heart rate rose from 143 to 163 across the work, with the set holding together before the late acceleration.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 7:56 | 3:58/km | 143 | 2:10 |
| 2 | 7:55 | 3:57/km | 154 | 2:13 |
| 3 | 7:57 | 3:59/km | 159 | 2:13 |
| 4 | 7:29 | 3:45/km | 163 | 2:14 |
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).
- Recoveries average 132s.
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
Recovery12%
Z2
Endurance32%
Z3
Tempo41%
Z4
Threshold15%
Z5
VO₂max0%
Pace
Z1
Easy9%
Z2
Endurance29%
Z3
Tempo59%
Z4
Threshold3%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance10%
Z3
Tempo20%
Z4
Threshold53%
Z5
VO₂max13%
Z6
Anaerobic4%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+5.9%
Effort & efficiency
0.72
Running effectiveness
speed per watt/kg, reps
5.9 w/kg
Power-to-weight
rep average
2.99
Efficiency factor
norm. power per bpm
1.02
Variability index
1.0 = perfectly even power
2.5%
Rep consistency
pace spread across reps, lower is tighter
1239 kJ
Total work
mechanical energy
650 kcal
Energy
estimated burn
725 bpk
Cardiac cost
heartbeats per km
15%
Above threshold
≥ 164 bpm (Z4+)
-0:13/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace24°C · +73 m
Actual
3:55/km
Grade-adjusted
3:55/km
Heat-adjusted
3:46/km
−9s/km
True effort
3:46/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.