Intervalsconfidence 0.83
VO2
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
VO2
Distance
13.3 km
Moving
58:29
Rep pace
3:22/km
Avg HR
157 bpm
Reps
14
Planned vs actual · TrainingPeaksPlanned 1:11:18 · 13.9 kmRan 58:29 · 13.3 kmIF 1.36TSS 178
Shape of the sessionEasyWorkFastest
warm up
cool down
0:0014 × work / float58:29
The decode
A progressive build followed by 10 × 400m was a VO2 interval session. The build moved through successive pace targets before the short-cycle work, making the session a progression into speed endurance rather than a set of detached sprints.
The four 500m reps accelerated from 3:43/km to 3:23/km. The 400m block then held between 3:12/km and 3:22/km; heart rate reached 178 and stayed at 176-177 across the final three repetitions.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:51 | 3:43/km | 141 | — |
| 2 | 1:48 | 3:36/km | 146 | — |
| 3 | 1:40 | 3:21/km | 148 | — |
| 4 | 1:42 | 3:23/km | 151 | 1:30 |
| 5 | 1:17 | 3:12/km | 168 | 0:40 |
| 6 | 1:20 | 3:19/km | 170 | 0:41 |
| 7 | 1:18 | 3:16/km | 157 | 0:44 |
| 8 | 1:19 | 3:17/km | 176 | 0:45 |
| 9 | 1:19 | 3:18/km | 175 | 0:45 |
| 10 | 1:20 | 3:20/km | 175 | 0:45 |
| 11 | 1:20 | 3:19/km | 176 | 0:41 |
| 12 | 1:21 | 3:22/km | 178 | 0:44 |
| 13 | 1:21 | 3:22/km | 176 | 0:42 |
| 14 | 1:20 | 3:19/km | 177 | 0:40 |
0.83
confidence
What the engine saw
- 14 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 47s.
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
Recovery10%
Z2
Endurance49%
Z3
Tempo11%
Z4
Threshold13%
Z5
VO₂max17%
Pace
Z1
Easy49%
Z2
Endurance17%
Z3
Tempo6%
Z4
Threshold6%
Z5
VO₂max17%
Z6
Speed5%
Power
Z1
Recovery10%
Z2
Endurance18%
Z3
Tempo36%
Z4
Threshold17%
Z5
VO₂max17%
Z6
Anaerobic2%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+11.9%
Effort & efficiency
0.78
Running effectiveness
speed per watt/kg, reps
6.4 w/kg
Power-to-weight
rep average
2.64
Efficiency factor
norm. power per bpm
1.07
Variability index
1.0 = perfectly even power
3.8%
Rep consistency
pace spread across reps, lower is tighter
1392 kJ
Total work
mechanical energy
940 kcal
Energy
estimated burn
708 bpk
Cardiac cost
heartbeats per km
30%
Above threshold
≥ 164 bpm (Z4+)
-0:02/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace24°C · +31 m
Actual
3:22/km
Grade-adjusted
3:22/km
Heat-adjusted
3:15/km
−7s/km
True effort
3:15/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.