Intervalsconfidence 0.88
15 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
15 × 400m
Distance
11.0 km
Moving
50:28
Rep pace
3:26/km
Avg HR
165 bpm
Reps
15
Shape of the sessionEasyWorkFastest
warm up
cool down
0:0015 × work / float50:28
The decode
A 15-rep interval set demanded repeated high-speed efforts with only 44-45 second recoveries. The short recoveries made pace control the central demand.
The set started at 3:25/km and reached 3:13/km before slowing late to 3:48/km. Heart rate rose from 168 on the first rep to 177 on the last, so the finish came under sustained cardiovascular load despite the pace loss.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:19 | 3:25/km | 168 | 0:45 |
| 2 | 1:19 | 3:16/km | 167 | 0:45 |
| 3 | 1:17 | 3:13/km | 171 | 0:44 |
| 4 | 1:18 | 3:17/km | 170 | 0:45 |
| 5 | 1:20 | 3:17/km | 176 | 0:45 |
| 6 | 1:22 | 3:26/km | 174 | 0:45 |
| 7 | 1:23 | 3:28/km | 171 | 0:45 |
| 8 | 1:21 | 3:24/km | 174 | 0:44 |
| 9 | 1:24 | 3:24/km | 173 | 0:44 |
| 10 | 1:21 | 3:19/km | 174 | 0:44 |
| 11 | 1:26 | 3:34/km | 176 | 0:45 |
| 12 | 1:25 | 3:30/km | 176 | 0:45 |
| 13 | 1:27 | 3:40/km | 176 | 0:45 |
| 14 | 1:23 | 3:26/km | 174 | 0:44 |
| 15 | 1:31 | 3:48/km | 177 | 0:45 |
0.88
confidence
What the engine saw
- 15 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 45s.
- Matches the athlete's own session label.
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
Recovery9%
Z2
Endurance17%
Z3
Tempo18%
Z4
Threshold23%
Z5
VO₂max32%
Pace
Z1
Easy49%
Z2
Endurance8%
Z3
Tempo4%
Z4
Threshold10%
Z5
VO₂max14%
Z6
Speed14%
Power
Z1
Recovery32%
Z2
Endurance30%
Z3
Tempo28%
Z4
Threshold9%
Z5
VO₂max1%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+5%
Effort & efficiency
0.97
Running effectiveness
speed per watt/kg, reps
5.0 w/kg
Power-to-weight
rep average
1.99
Efficiency factor
norm. power per bpm
1.15
Variability index
1.0 = perfectly even power
4.5%
Rep consistency
pace spread across reps, lower is tighter
909 kJ
Total work
mechanical energy
769 kcal
Energy
estimated burn
793 bpk
Cardiac cost
heartbeats per km
56%
Above threshold
≥ 164 bpm (Z4+)
-0:10/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace29°C · +15 m
Actual
3:25/km
Grade-adjusted
3:25/km
Heat-adjusted
3:15/km
−10s/km
True effort
3:15/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.