Intervalsconfidence 0.83
6 × 1km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
6 × 1km
Distance
9.0 km
Moving
39:16
Rep pace
3:49/km
Avg HR
167 bpm
Reps
6
Shape of the sessionEasyWorkFastest
warm up
cool down
0:006 × work / float39:16
The decode
A 3 × 2 km interval set was completed as six recorded 1 km laps. The paired efforts demanded continuity across each block rather than six separate short efforts.
The work blocks slowed from 3:39/km to 3:50/km to 3:59/km as average heart rate rose from 157 to 179 to 183. The individual reps faded from 3:34/km to 4:06/km, with heart rate reaching 187 on the final rep, so the set did not hold together.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 3:34 | 3:34/km | 157 | — |
| 2 | 3:43 | 3:43/km | 168 | 2:00 |
| 3 | 3:46 | 3:46/km | 179 | — |
| 4 | 3:53 | 3:53/km | 184 | 2:00 |
| 5 | 3:53 | 3:53/km | 183 | — |
| 6 | 4:06 | 4:06/km | 187 | 0:06 |
0.83
confidence
What the engine saw
- 6 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 82s.
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
Recovery20%
Z2
Endurance1%
Z3
Tempo20%
Z4
Threshold19%
Z5
VO₂max39%
Pace
Z1
Easy41%
Z2
Endurance11%
Z3
Tempo40%
Z4
Threshold6%
Z5
VO₂max1%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance27%
Z3
Tempo19%
Z4
Threshold46%
Z5
VO₂max8%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+17.7%
Effort & efficiency
0.72
Running effectiveness
speed per watt/kg, reps
6.1 w/kg
Power-to-weight
rep average
2.54
Efficiency factor
norm. power per bpm
1.04
Variability index
1.0 = perfectly even power
4.3%
Rep consistency
pace spread across reps, lower is tighter
1008 kJ
Total work
mechanical energy
628 kcal
Energy
estimated burn
754 bpk
Cardiac cost
heartbeats per km
59%
Above threshold
≥ 164 bpm (Z4+)
+0:14/km
Split balance
positive split, slower 2nd half
Conditions-adjusted pace28°C · +25 m
Actual
3:49/km
Grade-adjusted
3:49/km
Heat-adjusted
3:37/km
−12s/km
True effort
3:37/km
−12s/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.