Intervalsconfidence 0.83
4 × 1km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 1km
Distance
10.7 km
Moving
45:20
Rep pace
4:03/km
Avg HR
166 bpm
Reps
4
Planned vs actual · TrainingPeaksPlanned 53:39 · 12.6 kmRan 45:20 · 10.7 kmIF 1.53TSS 175
Shape of the sessionEasyWorkFastest
warm up
cool down
0:004 × work / float45:20
The decode
An adapted threshold set used two 2 km efforts followed by four 1 km efforts. The two-minute and one-minute jog recoveries made it a dense set, while 37 C added external load.
The 2 km work moved from 3:59/km at HR 161 to 4:03/km at HR 174. The 1 km reps then held at 4:01, 4:00, 4:05 and 4:04/km, with HR 177, 178, 179 and 175; the pace held together, and the final repetition did not carry the highest heart rate.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 4:01 | 4:01/km | 177 | 1:00 |
| 2 | 4:00 | 4:00/km | 178 | 1:00 |
| 3 | 4:05 | 4:05/km | 179 | 1:00 |
| 4 | 4:04 | 4:04/km | 175 | 1:00 |
0.83
confidence
What the engine saw
- 4 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 60s.
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
Recovery13%
Z2
Endurance7%
Z3
Tempo8%
Z4
Threshold23%
Z5
VO₂max48%
Pace
Z1
Easy23%
Z2
Endurance25%
Z3
Tempo53%
Z4
Threshold0%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance11%
Z3
Tempo38%
Z4
Threshold48%
Z5
VO₂max3%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+8.7%
Effort & efficiency
0.76
Running effectiveness
speed per watt/kg, reps
5.4 w/kg
Power-to-weight
rep average
2.52
Efficiency factor
norm. power per bpm
1.01
Variability index
1.0 = perfectly even power
0.8%
Rep consistency
pace spread across reps, lower is tighter
1361 kJ
Total work
mechanical energy
801 kcal
Energy
estimated burn
869 bpk
Cardiac cost
heartbeats per km
71%
Above threshold
≥ 164 bpm (Z4+)
+0:10/km
Split balance
positive split, slower 2nd half
Conditions-adjusted pace37°C · +36 m
Actual
4:03/km
Grade-adjusted
4:03/km
Heat-adjusted
3:43/km
−20s/km
True effort
3:43/km
−20s/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.