Intervalsconfidence 0.88
4 × 2km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 2km
Distance
13.1 km
Moving
54:57
Rep pace
3:44/km
Avg HR
165 bpm
Reps
4
Planned vs actual · TrainingPeaksPlanned 1:04:04 · 15.0 kmRan 54:57 · 13.1 kmIF 1.40TSS 178
Shape of the sessionEasyWorkFastest
warm up
cool down
0:004 × work / float54:57
The decode
It was a threshold set of four 2km reps above threshold, with 90s easy jogging recoveries, a warm-up and a cooldown.
The reps moved from 3:39/km to 3:43/km, then 3:46/km and 3:46/km, while heart rate rose from 175 to 179, 181 and 182. The set held together across the final two reps, with all recoveries at 1:30.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 7:19 | 3:39/km | 175 | 1:30 |
| 2 | 7:26 | 3:43/km | 179 | 1:30 |
| 3 | 7:33 | 3:46/km | 181 | 1:30 |
| 4 | 7:32 | 3:46/km | 182 | 1:30 |
0.88
confidence
What the engine saw
- 4 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 90s.
- Matches the athlete's own session label.
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
Recovery20%
Z2
Endurance15%
Z3
Tempo9%
Z4
Threshold12%
Z5
VO₂max45%
Pace
Z1
Easy44%
Z2
Endurance8%
Z3
Tempo39%
Z4
Threshold9%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance17%
Z3
Tempo36%
Z4
Threshold37%
Z5
VO₂max9%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+8.5%
Effort & efficiency
0.74
Running effectiveness
speed per watt/kg, reps
6.0 w/kg
Power-to-weight
rep average
2.58
Efficiency factor
norm. power per bpm
1.03
Variability index
1.0 = perfectly even power
1.3%
Rep consistency
pace spread across reps, lower is tighter
1489 kJ
Total work
mechanical energy
934 kcal
Energy
estimated burn
763 bpk
Cardiac cost
heartbeats per km
57%
Above threshold
≥ 164 bpm (Z4+)
-0:13/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace24°C · +45 m
Actual
3:44/km
Grade-adjusted
3:44/km
Heat-adjusted
3:36/km
−8s/km
True effort
3:36/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.