Intervalsconfidence 0.83
3 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
3 × 400m
Distance
11.8 km
Moving
48:08
Rep pace
3:20/km
Avg HR
166 bpm
Reps
3
Planned vs actual · TrainingPeaksPlanned 1:03:34 · 15.0 kmRan 48:08 · 11.8 kmIF 1.41TSS 157
Shape of the sessionEasyWorkFastest
warm up
cool down
0:003 × work / float48:08
The decode
A mixed speed set was built around 3km and 5km race pace. The sequence demanded repeated changes between short speed, kilometre work and longer fast reps, with little room to settle into one rhythm.
The kilometre block held tightly at 3:38, 3:35 and 3:37, while the 400m reps ran 1:21, 1:19 and 1:20. Heart rate reached 179 on the first kilometre rep before settling at 174 for the next two; the 400m work closed at 173 after 170 and 175.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:21 | 3:22/km | 170 | 1:46 |
| 2 | 1:19 | 3:18/km | 175 | 1:53 |
| 3 | 1:20 | 3:19/km | 173 | 1:53 |
0.83
confidence
What the engine saw
- 3 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 111s.
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
Recovery13%
Z2
Endurance9%
Z3
Tempo13%
Z4
Threshold25%
Z5
VO₂max40%
Pace
Z1
Easy13%
Z2
Endurance56%
Z3
Tempo4%
Z4
Threshold18%
Z5
VO₂max5%
Z6
Speed4%
Power
Z1
Recovery3%
Z2
Endurance10%
Z3
Tempo40%
Z4
Threshold34%
Z5
VO₂max10%
Z6
Anaerobic2%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+4.3%
Effort & efficiency
0.75
Running effectiveness
speed per watt/kg, reps
6.7 w/kg
Power-to-weight
rep average
2.61
Efficiency factor
norm. power per bpm
1.04
Variability index
1.0 = perfectly even power
0.8%
Rep consistency
pace spread across reps, lower is tighter
1408 kJ
Total work
mechanical energy
823 kcal
Energy
estimated burn
801 bpk
Cardiac cost
heartbeats per km
65%
Above threshold
≥ 164 bpm (Z4+)
-0:02/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace28°C · +33 m
Actual
3:20/km
Grade-adjusted
3:20/km
Heat-adjusted
3:10/km
−10s/km
True effort
3:10/km
−10s/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.