Intervalsconfidence 0.83
5 × 1km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
5 × 1km
Distance
8.3 km
Moving
35:40
Rep pace
3:44/km
Avg HR
158 bpm
Reps
5
Shape of the sessionEasyWorkFastest
warm up
cool down
0:005 × work / float35:40
The decode
It was a five-repetition 1km interval set, with 1:30 recoveries after the first four reps.
The reps ran 3:46, 3:51, 3:39, 3:40 and 3:42/km. Heart rate rose from 154 on the first rep to 170, 170, 174 and 173, while the work held together after the second rep.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 3:46 | 3:46/km | 154 | 1:30 |
| 2 | 3:51 | 3:51/km | 170 | 1:30 |
| 3 | 3:39 | 3:39/km | 170 | 1:30 |
| 4 | 3:40 | 3:40/km | 174 | 1:30 |
| 5 | 3:42 | 3:42/km | 173 | 0:11 |
0.83
confidence
What the engine saw
- 5 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 74s.
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
Recovery23%
Z2
Endurance18%
Z3
Tempo13%
Z4
Threshold27%
Z5
VO₂max19%
Pace
Z1
Easy49%
Z2
Endurance4%
Z3
Tempo34%
Z4
Threshold11%
Z5
VO₂max1%
Z6
Speed0%
Power
Z1
Recovery1%
Z2
Endurance28%
Z3
Tempo24%
Z4
Threshold33%
Z5
VO₂max14%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+5.9%
Effort & efficiency
0.73
Running effectiveness
speed per watt/kg, reps
6.1 w/kg
Power-to-weight
rep average
2.70
Efficiency factor
norm. power per bpm
1.04
Variability index
1.0 = perfectly even power
2.0%
Rep consistency
pace spread across reps, lower is tighter
945 kJ
Total work
mechanical energy
541 kcal
Energy
estimated burn
734 bpk
Cardiac cost
heartbeats per km
47%
Above threshold
≥ 164 bpm (Z4+)
-0:02/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace28°C · +40 m
Actual
3:44/km
Grade-adjusted
3:44/km
Heat-adjusted
3:33/km
−11s/km
True effort
3:33/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.