Intervalsconfidence 0.83
Fartlek Ladder ⛳️
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
Fartlek Ladder ⛳️
Distance
17.3 km
Moving
77:37
Rep pace
3:49/km
Avg HR
164 bpm
Reps
8
Planned vs actual · TrainingPeaksPlanned 1:20:00 · 17.9 kmRan 1:17:37 · 17.3 kmIF 1.32TSS 225
Shape of the sessionEasyWorkFastest
warm up
cool down
0:008 × work / float77:37
The decode
A two-set fartlek ladder used steady 8/10 efforts with half recoveries. The short recoveries kept the work continuous, and 36°C conditions made the second set the harder test.
The first set moved from 3:37/km to 3:47/km as heart rate rose from 178 to 182. The second set reached 4:02/km before the final 3:44/km rep, while heart rate was 176, 175, 179 and 178; the late slowdown did not carry into the final rep.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 2:00 | 3:37/km | 178 | 1:00 |
| 2 | 3:00 | 3:45/km | 180 | 1:30 |
| 3 | 3:00 | 3:44/km | 180 | 1:30 |
| 4 | 2:00 | 3:47/km | 182 | 1:00 |
| 5 | 2:00 | 3:55/km | 176 | 1:00 |
| 6 | 3:00 | 3:57/km | 175 | 1:30 |
| 7 | 3:00 | 4:02/km | 179 | 1:30 |
| 8 | 2:00 | 3:44/km | 178 | 1:00 |
0.83
confidence
What the engine saw
- 8 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 75s.
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
Recovery10%
Z2
Endurance18%
Z3
Tempo11%
Z4
Threshold24%
Z5
VO₂max36%
Pace
Z1
Easy58%
Z2
Endurance11%
Z3
Tempo28%
Z4
Threshold3%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery2%
Z2
Endurance22%
Z3
Tempo39%
Z4
Threshold27%
Z5
VO₂max10%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+4.9%
Effort & efficiency
0.74
Running effectiveness
speed per watt/kg, reps
5.9 w/kg
Power-to-weight
rep average
2.51
Efficiency factor
norm. power per bpm
1.04
Variability index
1.0 = perfectly even power
3.4%
Rep consistency
pace spread across reps, lower is tighter
2218 kJ
Total work
mechanical energy
1252 kcal
Energy
estimated burn
887 bpk
Cardiac cost
heartbeats per km
60%
Above threshold
≥ 164 bpm (Z4+)
-0:25/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace36°C · +91 m
Actual
3:49/km
Grade-adjusted
3:49/km
Heat-adjusted
3:31/km
−18s/km
True effort
3:31/km
−18s/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.