Intervalsconfidence 0.83
5 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
5 × 400m
Distance
17.8 km
Moving
86:52
Rep pace
3:36/km
Avg HR
137 bpm
Reps
5
Planned vs actual · TrainingPeaksPlanned 12.0 kmRan 1:26:52 · 17.8 kmIF 1.44TSS 299
Shape of the sessionEasyWorkFastest
warm up
cool down
0:005 × work / float86:52
The decode
This was a five-rep interval set in a reduced-volume week. The cut-down structure demanded a faster second half rather than a uniform opening pace, with the work settling into its quickest range late in the set.
The set accelerated after the opening two reps, moving from 3:45/km and 3:49/km to 3:30/km, 3:25/km and 3:30/km. Heart rate rose from 119 to 154 by the fourth rep, then eased to 151 on the final rep, so the pace held together after the peak effort.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:31 | 3:45/km | 119 | 0:47 |
| 2 | 1:30 | 3:49/km | 126 | 0:38 |
| 3 | 1:30 | 3:30/km | 147 | 0:43 |
| 4 | 1:30 | 3:25/km | 154 | 0:44 |
| 5 | 1:33 | 3:30/km | 151 | 4:47 |
0.83
confidence
What the engine saw
- 5 work intervals detected from lap markers, confirmed by clear pace separation.
- Rep paces descend across the set (a cut-down / progression).
- Recoveries average 92s.
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
Recovery68%
Z2
Endurance28%
Z3
Tempo2%
Z4
Threshold1%
Z5
VO₂max0%
Pace
Z1
Easy53%
Z2
Endurance39%
Z3
Tempo2%
Z4
Threshold4%
Z5
VO₂max3%
Z6
Speed0%
Power
Z1
Recovery8%
Z2
Endurance18%
Z3
Tempo45%
Z4
Threshold24%
Z5
VO₂max5%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+1%
Effort & efficiency
0.78
Running effectiveness
speed per watt/kg, reps
6.0 w/kg
Power-to-weight
rep average
2.91
Efficiency factor
norm. power per bpm
1.07
Variability index
1.0 = perfectly even power
4.3%
Rep consistency
pace spread across reps, lower is tighter
2053 kJ
Total work
mechanical energy
1237 kcal
Energy
estimated burn
714 bpk
Cardiac cost
heartbeats per km
1%
Above threshold
≥ 164 bpm (Z4+)
+0:10/km
Split balance
positive split, slower 2nd half
Conditions-adjusted pace20°C · +96 m
Actual
3:35/km
Grade-adjusted
3:35/km
Heat-adjusted
3:31/km
−4s/km
True effort
3:31/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.