Intervalsconfidence 0.83
10 × 400m track
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
10 × 400m track
Distance
10.0 km
Moving
41:30
Rep pace
3:33/km
Avg HR
162 bpm
Reps
10
Planned vs actual · TrainingPeaksPlanned 1:02:31 · 12.0 kmRan 41:30 · 10.0 kmIF 1.43TSS 139
Shape of the sessionEasyWorkFastest
warm up
cool down
0:0010 × work / float41:30
The decode
A track session with 2km at threshold and 10 × 400m. It demanded threshold-or-quicker running under short static recoveries, with a longer reset separating the work into two blocks.
The reps moved from 3:37/km to 3:29/km across the opening block, then held between 3:30/km and 3:35/km in the second. Heart rate rose from 166 on the first rep to 177 on the last, while the pace stayed within 3:30/km and 3:35/km in the closing block.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:27 | 3:37/km | 166 | 0:30 |
| 2 | 1:25 | 3:33/km | 172 | 0:30 |
| 3 | 1:27 | 3:38/km | 172 | 0:30 |
| 4 | 1:25 | 3:32/km | 164 | 0:30 |
| 5 | 1:24 | 3:29/km | 174 | 0:30 |
| 6 | 1:24 | 3:30/km | 165 | 0:30 |
| 7 | 1:24 | 3:31/km | 174 | 0:30 |
| 8 | 1:26 | 3:35/km | 173 | 0:30 |
| 9 | 1:25 | 3:32/km | 175 | 0:30 |
| 10 | 1:24 | 3:30/km | 177 | 0:30 |
0.83
confidence
What the engine saw
- 10 work intervals detected from lap markers, confirmed by clear pace separation.
- 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
Recovery8%
Z2
Endurance24%
Z3
Tempo4%
Z4
Threshold36%
Z5
VO₂max27%
Pace
Z1
Easy35%
Z2
Endurance12%
Z3
Tempo32%
Z4
Threshold20%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery1%
Z2
Endurance18%
Z3
Tempo25%
Z4
Threshold23%
Z5
VO₂max32%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+2.9%
Effort & efficiency
0.82
Running effectiveness
speed per watt/kg, reps
5.7 w/kg
Power-to-weight
rep average
2.72
Efficiency factor
norm. power per bpm
1.04
Variability index
1.0 = perfectly even power
1.3%
Rep consistency
pace spread across reps, lower is tighter
1200 kJ
Total work
mechanical energy
677 kcal
Energy
estimated burn
762 bpk
Cardiac cost
heartbeats per km
63%
Above threshold
≥ 164 bpm (Z4+)
+0:04/km
Split balance
positive split, slower 2nd half
Conditions-adjusted pace23°C · +18 m
Actual
3:33/km
Grade-adjusted
3:33/km
Heat-adjusted
3:26/km
−7s/km
True effort
3:26/km
−7s/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.