Intervalsconfidence 0.83
4 × 1.6km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 1.6km
Distance
17.1 km
Moving
73:13
Rep pace
3:49/km
Avg HR
150 bpm
Reps
4
Planned vs actual · TrainingPeaksPlanned 1:13:44 · 17.0 kmRan 1:13:13 · 17.1 kmIF 1.32TSS 211
Shape of the sessionEasyWorkFastest
warm up
cool down
0:004 × work / float73:13
The decode
It was a four-repetition broken 8-minute threshold set, with 6 minutes at threshold pace followed by 2 minutes slightly faster at anaerobic pace.
The 6-minute portions ran at 3:42/km, 3:45/km, 3:54/km and 3:53/km. The 2-minute portions stayed between 3:29/km and 3:31/km, while heart rate rose from 152 and 145 in the first two work portions to 168 and 169 in the last two.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 6:00 | 3:42/km | 152 | — |
| 2 | 6:00 | 3:45/km | 145 | — |
| 3 | 6:00 | 3:54/km | 168 | — |
| 4 | 6:00 | 3:53/km | 169 | — |
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
Recovery41%
Z2
Endurance27%
Z3
Tempo3%
Z4
Threshold21%
Z5
VO₂max8%
Pace
Z1
Easy55%
Z2
Endurance8%
Z3
Tempo20%
Z4
Threshold14%
Z5
VO₂max3%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance26%
Z3
Tempo40%
Z4
Threshold34%
Z5
VO₂max0%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+10.6%
Effort & efficiency
0.76
Running effectiveness
speed per watt/kg, reps
5.8 w/kg
Power-to-weight
rep average
2.67
Efficiency factor
norm. power per bpm
1.03
Variability index
1.0 = perfectly even power
2.3%
Rep consistency
pace spread across reps, lower is tighter
1860 kJ
Total work
mechanical energy
999 kcal
Energy
estimated burn
706 bpk
Cardiac cost
heartbeats per km
29%
Above threshold
≥ 164 bpm (Z4+)
+0:00/km
Split balance
even split
Conditions-adjusted pace25°C
Actual
3:49/km
Grade-adjusted
3:49/km
Heat-adjusted
3:40/km
−9s/km
True effort
3:40/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.