Intervalsconfidence 0.83
3 × 1km
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
3 × 1km
Distance
8.8 km
Moving
38:28
Rep pace
3:46/km
Avg HR
135 bpm
Reps
3
Planned vs actual · TrainingPeaksPlanned 42:40 · 10.0 kmRan 38:28 · 8.8 kmIF 1.36TSS 117
Shape of the sessionEasyWorkFastest
warm up
cool down
0:003 × work / float38:28
The decode
This was a threshold set of three 1km reps. It demanded sustained threshold output in heat and direct sun, which made the intended extension unsustainable and forced a slower modification.
The reps slowed from 3:42/km to 3:49/km as heart rate rose from 172 to 181, so the effort tightened while pace drifted. The later heart-rate readings were unusable after the monitor fell, and the session did not hold together beyond the opening work.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 3:42 | 3:42/km | 172 | — |
| 2 | 3:46 | 3:46/km | 179 | — |
| 3 | 3:49 | 3:49/km | 181 | 4:09 |
0.83
confidence
What the engine saw
- 3 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 249s.
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
Recovery36%
Z2
Endurance15%
Z3
Tempo16%
Z4
Threshold5%
Z5
VO₂max27%
Pace
Z1
Easy37%
Z2
Endurance33%
Z3
Tempo28%
Z4
Threshold2%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance15%
Z3
Tempo41%
Z4
Threshold43%
Z5
VO₂max1%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR-51.2%
Effort & efficiency
0.75
Running effectiveness
speed per watt/kg, reps
5.9 w/kg
Power-to-weight
rep average
3.05
Efficiency factor
norm. power per bpm
1.02
Variability index
1.0 = perfectly even power
1.3%
Rep consistency
pace spread across reps, lower is tighter
1029 kJ
Total work
mechanical energy
558 kcal
Energy
estimated burn
648 bpk
Cardiac cost
heartbeats per km
33%
Above threshold
≥ 164 bpm (Z4+)
-0:03/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace38°C · +25 m
Actual
3:46/km
Grade-adjusted
3:46/km
Heat-adjusted
3:27/km
−19s/km
True effort
3:27/km
−19s/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.