Intervalsconfidence 0.83
4 × 1km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 1km
Distance
10.6 km
Moving
47:17
Rep pace
3:45/km
Avg HR
161 bpm
Reps
4
Shape of the sessionEasyWorkFastest
warm up
cool down
0:004 × work / float47:17
The decode
It was a four-repetition 1km interval set, with 1:30 recoveries after the first three reps and 0:42 after the fourth.
The reps ran 3:51/km, 3:45/km, 3:38/km and 3:45/km. Heart rate rose from 163 to 186 across the set, with the fastest rep third and the final rep returning to 3:45/km.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 3:51 | 3:51/km | 163 | 1:30 |
| 2 | 3:45 | 3:45/km | 166 | 1:30 |
| 3 | 3:38 | 3:38/km | 183 | 1:30 |
| 4 | 3:45 | 3:45/km | 186 | 0:42 |
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 78s.
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
Recovery12%
Z2
Endurance22%
Z3
Tempo30%
Z4
Threshold15%
Z5
VO₂max22%
Pace
Z1
Easy35%
Z2
Endurance35%
Z3
Tempo22%
Z4
Threshold7%
Z5
VO₂max1%
Z6
Speed0%
Power
Z1
Recovery1%
Z2
Endurance11%
Z3
Tempo51%
Z4
Threshold32%
Z5
VO₂max4%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+1.5%
Effort & efficiency
0.76
Running effectiveness
speed per watt/kg, reps
5.9 w/kg
Power-to-weight
rep average
2.59
Efficiency factor
norm. power per bpm
1.02
Variability index
1.0 = perfectly even power
2.2%
Rep consistency
pace spread across reps, lower is tighter
1187 kJ
Total work
mechanical energy
743 kcal
Energy
estimated burn
729 bpk
Cardiac cost
heartbeats per km
37%
Above threshold
≥ 164 bpm (Z4+)
-0:38/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace25°C · +62 m
Actual
3:45/km
Grade-adjusted
3:45/km
Heat-adjusted
3:36/km
−9s/km
True effort
3:36/km
−9s/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.