Intervalsconfidence 0.83
800s hills
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
800s hills
Distance
15.0 km
Moving
71:25
Rep pace
3:31/km
Avg HR
154 bpm
Reps
6
Planned vs actual · TrainingPeaksPlanned 16.0 kmRan 1:11:25 · 15.0 kmIF 1.32TSS 207
Shape of the sessionEasyWorkFastest
warm up
cool down
0:006 × work / float71:25
The decode
Five 800m intervals followed a build and recovery. It was a VO2 interval session, with the fast work separated from the opening progression and the cooldown made more demanding by stairs and 20% hills.
The 800m set held between 3:24/km and 3:34/km, with the final rep at 3:27/km. Heart rate rose from 171 to 176 across the set, while the 1:00 recoveries kept the effort elevated rather than resetting it.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:51 | 3:41/km | 169 | 4:48 |
| 2 | 2:43 | 3:24/km | 171 | 1:00 |
| 3 | 2:49 | 3:31/km | 172 | 1:00 |
| 4 | 2:47 | 3:29/km | 174 | 1:00 |
| 5 | 2:51 | 3:34/km | 173 | 1:00 |
| 6 | 2:45 | 3:27/km | 176 | 1:00 |
0.83
confidence
What the engine saw
- 6 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 98s.
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
Recovery27%
Z2
Endurance24%
Z3
Tempo16%
Z4
Threshold21%
Z5
VO₂max13%
Pace
Z1
Easy68%
Z2
Endurance11%
Z3
Tempo6%
Z4
Threshold11%
Z5
VO₂max5%
Z6
Speed0%
Power
Z1
Recovery14%
Z2
Endurance26%
Z3
Tempo28%
Z4
Threshold20%
Z5
VO₂max11%
Z6
Anaerobic1%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+8%
Effort & efficiency
0.77
Running effectiveness
speed per watt/kg, reps
6.2 w/kg
Power-to-weight
rep average
2.66
Efficiency factor
norm. power per bpm
1.09
Variability index
1.0 = perfectly even power
2.7%
Rep consistency
pace spread across reps, lower is tighter
1767 kJ
Total work
mechanical energy
1059 kcal
Energy
estimated burn
811 bpk
Cardiac cost
heartbeats per km
33%
Above threshold
≥ 164 bpm (Z4+)
-0:13/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace15°C · +244 m
Actual
3:31/km
Grade-adjusted
3:31/km
Heat-adjusted
3:31/km
True effort
3:31/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.