Intervalsconfidence 0.83
9 × 40s on / 40s off
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
9 × 40s on / 40s off
Distance
18.7 km
Moving
88:29
Rep pace
3:08/km
Avg HR
138 bpm
Reps
9
Planned vs actual · TrainingPeaksPlanned 18.0 kmRan 1:28:29 · 18.7 kmIF 1.47TSS 318
Shape of the sessionEasyWorkFastest
warm up
cool down
0:009 × work / float88:29
The decode
Nine 40-second efforts off 40-second recoveries formed a short-interval session. The equal work and recovery periods demanded repeated speed with limited clearance between bouts.
The set accelerated through rep five, softened across reps six to eight, then closed with the fastest rep at 2:45/km. Heart rate reached 154 on the final effort, with the response highest across the closing reps.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 0:40 | 3:18/km | 139 | 0:40 |
| 2 | 0:40 | 3:10/km | 131 | 0:40 |
| 3 | 0:40 | 3:10/km | 125 | 0:40 |
| 4 | 0:40 | 3:05/km | 138 | 0:40 |
| 5 | 0:40 | 3:00/km | 146 | 0:40 |
| 6 | 0:40 | 3:10/km | 137 | 0:40 |
| 7 | 0:40 | 3:14/km | 141 | 0:40 |
| 8 | 0:40 | 3:16/km | 150 | 0:40 |
| 9 | 0:40 | 2:45/km | 154 | 0:40 |
0.83
confidence
What the engine saw
- 9 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 40s.
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
Recovery75%
Z2
Endurance24%
Z3
Tempo1%
Z4
Threshold0%
Z5
VO₂max0%
Pace
Z1
Easy41%
Z2
Endurance42%
Z3
Tempo4%
Z4
Threshold7%
Z5
VO₂max2%
Z6
Speed4%
Power
Z1
Recovery10%
Z2
Endurance16%
Z3
Tempo47%
Z4
Threshold15%
Z5
VO₂max10%
Z6
Anaerobic3%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+6.7%
Effort & efficiency
0.99
Running effectiveness
speed per watt/kg, reps
5.4 w/kg
Power-to-weight
rep average
3.00
Efficiency factor
norm. power per bpm
1.10
Variability index
1.0 = perfectly even power
5.0%
Rep consistency
pace spread across reps, lower is tighter
2306 kJ
Total work
mechanical energy
1262 kcal
Energy
estimated burn
752 bpk
Cardiac cost
heartbeats per km
0%
Above threshold
≥ 164 bpm (Z4+)
+0:00/km
Split balance
even split
Conditions-adjusted pace20°C · +76 m
Actual
3:07/km
Grade-adjusted
3:07/km
Heat-adjusted
3:03/km
−4s/km
True effort
3:03/km
−4s/km
The rep pace re-expressed for flat ground and cool air, the effort, not the clock. Adjustments are modest on this one; on a hot day or a hilly route this is where the real work hides.