Intervalsconfidence 0.83
8 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
8 × 400m
Distance
8.3 km
Moving
36:34
Rep pace
3:36/km
Avg HR
162 bpm
Reps
8
Shape of the sessionEasyWorkFastest
warm up
cool down
0:008 × work / float36:34
The decode
This was an interval set of eight 1:30 work repetitions with 1:30 recoveries.
The repetitions ranged from 3:29/km to 3:43/km. Pace slowed through the fifth repetition before returning to 3:37/km, 3:34/km and 3:31/km across the final three. Heart rate rose from 158 on the first repetition to 170 on the seventh, with a session maximum of 176.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:30 | 3:34/km | 158 | 1:30 |
| 2 | 1:30 | 3:29/km | 161 | 1:30 |
| 3 | 1:30 | 3:38/km | 164 | 1:30 |
| 4 | 1:30 | 3:42/km | 163 | 1:30 |
| 5 | 1:30 | 3:43/km | 168 | 1:30 |
| 6 | 1:30 | 3:37/km | 167 | 1:30 |
| 7 | 1:30 | 3:34/km | 170 | 1:30 |
| 8 | 1:30 | 3:31/km | 168 | 1:30 |
0.83
confidence
What the engine saw
- 8 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 90s.
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
Recovery4%
Z2
Endurance14%
Z3
Tempo28%
Z4
Threshold52%
Z5
VO₂max3%
Pace
Z1
Easy45%
Z2
Endurance23%
Z3
Tempo7%
Z4
Threshold23%
Z5
VO₂max3%
Z6
Speed0%
Power
Z1
Recovery2%
Z2
Endurance30%
Z3
Tempo27%
Z4
Threshold20%
Z5
VO₂max17%
Z6
Anaerobic5%
Z7
Neuro0%
Aerobic decoupling · Pa:HR-0.9%
Effort & efficiency
0.70
Running effectiveness
speed per watt/kg, reps
6.6 w/kg
Power-to-weight
rep average
2.65
Efficiency factor
norm. power per bpm
1.05
Variability index
1.0 = perfectly even power
2.2%
Rep consistency
pace spread across reps, lower is tighter
899 kJ
Total work
mechanical energy
579 kcal
Energy
estimated burn
715 bpk
Cardiac cost
heartbeats per km
55%
Above threshold
≥ 164 bpm (Z4+)
-0:25/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace17°C · +16 m
Actual
3:36/km
Grade-adjusted
3:36/km
Heat-adjusted
3:34/km
−2s/km
True effort
3:34/km
−2s/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.