Intervalsconfidence 0.83
12 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
12 × 400m
Distance
16.8 km
Moving
85:10
Rep pace
3:31/km
Avg HR
140 bpm
Reps
12
Planned vs actual · TrainingPeaksPlanned 22.0 kmRan 1:25:10 · 16.8 kmIF 1.42TSS 283
Shape of the sessionEasyWorkFastest
warm up
cool down
0:0012 × work / float85:10
The decode
Twelve 90-second reps formed a cut-down interval set. One-minute recoveries through rep eight gave way to 45-second recoveries for the final three, making the finish progressively harder rather than allowing a full reset.
The pace descended from 3:44/km to 3:18/km, with 3:18/km repeated before a 3:21/km close. Heart rate reached 168 on rep 11 and remained at 160 on the final rep, so the faster finish held despite the shortened recoveries.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:30 | 3:44/km | 151 | 1:00 |
| 2 | 1:30 | 3:40/km | 147 | 1:00 |
| 3 | 1:30 | 3:37/km | 140 | 1:00 |
| 4 | 1:30 | 3:35/km | 145 | 1:00 |
| 5 | 1:30 | 3:33/km | 131 | 1:00 |
| 6 | 1:30 | 3:31/km | 126 | 1:00 |
| 7 | 1:30 | 3:35/km | 139 | 1:00 |
| 8 | 1:30 | 3:32/km | 133 | 1:00 |
| 9 | 1:30 | 3:25/km | 142 | 0:45 |
| 10 | 1:30 | 3:18/km | 156 | 0:45 |
| 11 | 1:30 | 3:18/km | 168 | 0:45 |
| 12 | 1:30 | 3:21/km | 160 | 6:02 |
0.83
confidence
What the engine saw
- 12 work intervals detected from lap markers, confirmed by clear pace separation.
- Rep paces descend across the set (a cut-down / progression).
- Recoveries average 81s.
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
Recovery56%
Z2
Endurance36%
Z3
Tempo5%
Z4
Threshold3%
Z5
VO₂max0%
Pace
Z1
Easy74%
Z2
Endurance8%
Z3
Tempo3%
Z4
Threshold9%
Z5
VO₂max6%
Z6
Speed0%
Power
Z1
Recovery8%
Z2
Endurance32%
Z3
Tempo35%
Z4
Threshold12%
Z5
VO₂max11%
Z6
Anaerobic1%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+0.9%
Effort & efficiency
0.79
Running effectiveness
speed per watt/kg, reps
6.0 w/kg
Power-to-weight
rep average
2.87
Efficiency factor
norm. power per bpm
1.11
Variability index
1.0 = perfectly even power
3.9%
Rep consistency
pace spread across reps, lower is tighter
2177 kJ
Total work
mechanical energy
1209 kcal
Energy
estimated burn
841 bpk
Cardiac cost
heartbeats per km
3%
Above threshold
≥ 164 bpm (Z4+)
-0:10/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace22°C · +131 m
Actual
3:30/km
Grade-adjusted
3:30/km
Heat-adjusted
3:25/km
−5s/km
True effort
3:25/km
−5s/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.