Intervalsconfidence 0.83
5 × 400m hills
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
5 × 400m hills
Distance
15.6 km
Moving
66:50
Rep pace
3:30/km
Avg HR
161 bpm
Reps
5
Planned vs actual · TrainingPeaksPlanned 1:09:33 · 15.8 kmRan 1:06:50 · 15.6 kmIF 1.60TSS 284
Shape of the sessionEasyWorkFastest
warm up
cool down
0:005 × work / float66:50
The decode
A threshold-plus-VO2 hills session combined sustained threshold blocks with faster 400m repetitions. The rolling terrain and short 45-second recoveries made the final work a speed stimulus under accumulated load rather than an isolated rep set.
The sequence opened at 3:31/km, quickened to 3:26/km, slowed to 3:35/km, then returned to 3:27/km and 3:30/km. Heart rate rose from 166 to 175 by the third rep and finished at 171, so the set held its pace after the threshold work.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:24 | 3:31/km | 166 | 0:45 |
| 2 | 1:22 | 3:26/km | 173 | 0:45 |
| 3 | 1:26 | 3:35/km | 175 | 0:45 |
| 4 | 1:23 | 3:27/km | 172 | 0:45 |
| 5 | 1:24 | 3:30/km | 171 | 0:45 |
0.83
confidence
What the engine saw
- 5 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 45s.
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
Recovery24%
Z2
Endurance12%
Z3
Tempo11%
Z4
Threshold21%
Z5
VO₂max31%
Pace
Z1
Easy46%
Z2
Endurance7%
Z3
Tempo18%
Z4
Threshold27%
Z5
VO₂max1%
Z6
Speed0%
Power
Z1
Recovery5%
Z2
Endurance18%
Z3
Tempo34%
Z4
Threshold25%
Z5
VO₂max13%
Z6
Anaerobic5%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+6.8%
Effort & efficiency
0.82
Running effectiveness
speed per watt/kg, reps
5.8 w/kg
Power-to-weight
rep average
2.75
Efficiency factor
norm. power per bpm
1.08
Variability index
1.0 = perfectly even power
1.6%
Rep consistency
pace spread across reps, lower is tighter
1787 kJ
Total work
mechanical energy
1116 kcal
Energy
estimated burn
753 bpk
Cardiac cost
heartbeats per km
52%
Above threshold
≥ 164 bpm (Z4+)
-0:04/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace31°C · +149 m
Actual
3:30/km
Grade-adjusted
3:30/km
Heat-adjusted
3:17/km
−13s/km
True effort
3:17/km
−13s/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.