Intervalsconfidence 0.83
4 × 1km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 1km
Distance
9.2 km
Moving
53:18
Rep pace
4:25/km
Avg HR
162 bpm
Reps
4
Shape of the sessionEasyWorkFastest
warm up
0:004 × work / float53:18
The decode
Four 1km reps made up a cut-down interval set. It demanded changing pace rather than uniform repetition, with the uneven middle rep making the final acceleration the key execution point.
The reps ran at 4:36/km, 4:22/km, 4:29/km and 4:13/km, while heart rate rose from 139 to 188. The progression was interrupted by the third rep but closed with the fastest split and highest rep heart rate.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 4:36 | 4:36/km | 139 | — |
| 2 | 4:22 | 4:22/km | 156 | 6:55 |
| 3 | 4:30 | 4:29/km | 171 | — |
| 4 | 4:13 | 4:13/km | 188 | — |
0.83
confidence
What the engine saw
- 4 work intervals detected from lap markers, confirmed by clear pace separation.
- Rep paces descend across the set (a cut-down / progression).
- Recoveries average 415s.
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
Recovery17%
Z2
Endurance22%
Z3
Tempo17%
Z4
Threshold13%
Z5
VO₂max32%
Pace
Z1
Easy58%
Z2
Endurance41%
Z3
Tempo2%
Z4
Threshold0%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery45%
Z2
Endurance12%
Z3
Tempo17%
Z4
Threshold26%
Z5
VO₂max1%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+20.3%
Effort & efficiency
0.73
Running effectiveness
speed per watt/kg, reps
5.2 w/kg
Power-to-weight
rep average
2.07
Efficiency factor
norm. power per bpm
1.11
Variability index
1.0 = perfectly even power
3.2%
Rep consistency
pace spread across reps, lower is tighter
1238 kJ
Total work
mechanical energy
837 kcal
Energy
estimated burn
1131 bpk
Cardiac cost
heartbeats per km
45%
Above threshold
≥ 164 bpm (Z4+)
+0:57/km
Split balance
positive split, slower 2nd half
Conditions-adjusted pace25°C · +45 m
Actual
4:25/km
Grade-adjusted
4:25/km
Heat-adjusted
4:14/km
−11s/km
True effort
4:14/km
−11s/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.