Intervalsconfidence 0.83
24 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
24 × 400m
Distance
16.8 km
Moving
75:18
Rep pace
3:40/km
Avg HR
160 bpm
Reps
24
Planned vs actual · TrainingPeaksPlanned 1:18:50 · 16.0 kmRan 1:15:18 · 16.8 kmIF 1.53TSS 293
Shape of the sessionEasyWorkFastest
warm up
cool down
0:0024 × work / float75:18
The decode
Twenty-four 400m reps formed a sub-threshold set, with the final 10 available for a lift if the effort remained sound. The 30s recoveries kept the work densely packed rather than resetting each rep.
The set progressed from 3:50/km on rep 7 to 3:33/km on rep 16 and 3:24/km on rep 24. Heart rate rose from 127 on rep 1 to 177 on rep 24, while the acceleration held through the closing reps.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:30 | 3:45/km | 127 | 0:30 |
| 2 | 1:30 | 3:46/km | 160 | 0:30 |
| 3 | 1:30 | 3:45/km | 161 | 0:30 |
| 4 | 1:29 | 3:43/km | 160 | 0:30 |
| 5 | 1:30 | 3:46/km | 161 | 0:30 |
| 6 | 1:29 | 3:43/km | 161 | 0:30 |
| 7 | 1:32 | 3:50/km | 162 | 0:30 |
| 8 | 1:30 | 3:45/km | 163 | 0:30 |
| 9 | 1:29 | 3:42/km | 164 | 0:30 |
| 10 | 1:27 | 3:38/km | 164 | 0:30 |
| 11 | 1:31 | 3:47/km | 166 | 0:30 |
| 12 | 1:30 | 3:45/km | 164 | 0:30 |
| 13 | 1:29 | 3:43/km | 167 | 0:30 |
| 14 | 1:28 | 3:39/km | 168 | 0:30 |
| 15 | 1:27 | 3:39/km | 171 | 0:30 |
| 16 | 1:25 | 3:33/km | 172 | 0:30 |
| 17 | 1:26 | 3:36/km | 172 | 0:30 |
| 18 | 1:27 | 3:37/km | 172 | 0:30 |
| 19 | 1:27 | 3:37/km | 172 | 0:30 |
| 20 | 1:27 | 3:38/km | 173 | 0:30 |
| 21 | 1:27 | 3:37/km | 173 | 0:30 |
| 22 | 1:25 | 3:32/km | 174 | 0:30 |
| 23 | 1:23 | 3:29/km | 176 | 0:30 |
| 24 | 1:22 | 3:24/km | 177 | 0:30 |
0.83
confidence
What the engine saw
- 24 work intervals detected from lap markers, confirmed by clear pace separation.
- Rep paces descend across the set (a cut-down / progression).
- Recoveries average 30s.
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
Endurance14%
Z3
Tempo20%
Z4
Threshold39%
Z5
VO₂max15%
Pace
Z1
Easy28%
Z2
Endurance28%
Z3
Tempo22%
Z4
Threshold22%
Z5
VO₂max1%
Z6
Speed0%
Power
Z1
Recovery12%
Z2
Endurance5%
Z3
Tempo23%
Z4
Threshold43%
Z5
VO₂max13%
Z6
Anaerobic3%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+10.1%
Effort & efficiency
0.77
Running effectiveness
speed per watt/kg, reps
5.9 w/kg
Power-to-weight
rep average
2.74
Efficiency factor
norm. power per bpm
1.09
Variability index
1.0 = perfectly even power
2.8%
Rep consistency
pace spread across reps, lower is tighter
1855 kJ
Total work
mechanical energy
1216 kcal
Energy
estimated burn
726 bpk
Cardiac cost
heartbeats per km
54%
Above threshold
≥ 164 bpm (Z4+)
-0:06/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace31°C · +75 m
Actual
3:40/km
Grade-adjusted
3:40/km
Heat-adjusted
3:27/km
−13s/km
True effort
3:27/km
−13s/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.