Intervalsconfidence 0.83
4 × 500m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 500m
Distance
9.1 km
Moving
38:03
Rep pace
3:41/km
Avg HR
158 bpm
Reps
4
Planned vs actual · TrainingPeaksPlanned 8.0 kmRan 38:03 · 9.1 kmIF 1.38TSS 119
Shape of the sessionEasyWorkFastest
warm up
cool down
0:004 × work / float38:03
The decode
This was an activation and power set built around four 2:00 efforts, with 2:00 recoveries and additional 0:30 surges recorded between the work intervals.
The efforts progressed from 3:43/km to 3:38/km: 3:43/km, 3:44/km, 3:40/km and 3:38/km. Heart rate rose from 157 to 171, with the progression intact through the final repetition.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 2:00 | 3:43/km | 157 | 2:00 |
| 2 | 2:00 | 3:44/km | 163 | 2:00 |
| 3 | 2:00 | 3:40/km | 166 | 2:00 |
| 4 | 2:00 | 3:38/km | 171 | 2:00 |
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 120s.
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
Endurance11%
Z3
Tempo37%
Z4
Threshold30%
Z5
VO₂max5%
Pace
Z1
Easy12%
Z2
Endurance59%
Z3
Tempo17%
Z4
Threshold10%
Z5
VO₂max1%
Z6
Speed1%
Power
Z1
Recovery1%
Z2
Endurance2%
Z3
Tempo51%
Z4
Threshold32%
Z5
VO₂max13%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+6.8%
Effort & efficiency
0.74
Running effectiveness
speed per watt/kg, reps
6.1 w/kg
Power-to-weight
rep average
2.70
Efficiency factor
norm. power per bpm
1.02
Variability index
1.0 = perfectly even power
1.1%
Rep consistency
pace spread across reps, lower is tighter
978 kJ
Total work
mechanical energy
615 kcal
Energy
estimated burn
677 bpk
Cardiac cost
heartbeats per km
35%
Above threshold
≥ 164 bpm (Z4+)
-0:01/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace27°C · +26 m
Actual
3:41/km
Grade-adjusted
3:41/km
Heat-adjusted
3:31/km
−10s/km
True effort
3:31/km
−10s/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.