Intervalsconfidence 0.83
5 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
5 × 400m
Distance
24.0 km
Moving
114:00
Rep pace
3:39/km
Avg HR
158 bpm
Reps
5
Planned vs actual · TrainingPeaksPlanned 12.0 kmRan 1:54:00 · 24.0 kmIF 1.31TSS 328
Shape of the sessionEasyWorkFastest
warm up
cool down
0:005 × work / float114:00
The decode
A long warm-up, four 4-minute efforts and five 90-second reps made this a mixed interval session. The longer work came before the shorter repetitions, demanding sustained output before the closing speed.
The 90-second set held at 3:42/km, 3:39/km, 3:44/km and 3:42/km before closing at 3:30/km, with 45-second recoveries. Heart rate rose from 167 to 173, and the set finished fastest rather than fading.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:30 | 3:42/km | 167 | 0:45 |
| 2 | 1:30 | 3:39/km | 169 | 0:45 |
| 3 | 1:30 | 3:44/km | 169 | 0:45 |
| 4 | 1:30 | 3:42/km | 171 | 0:45 |
| 5 | 1:30 | 3:30/km | 173 | 4:35 |
0.83
confidence
What the engine saw
- 5 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 91s.
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
Recovery11%
Z2
Endurance23%
Z3
Tempo37%
Z4
Threshold15%
Z5
VO₂max13%
Pace
Z1
Easy44%
Z2
Endurance41%
Z3
Tempo8%
Z4
Threshold6%
Z5
VO₂max2%
Z6
Speed0%
Power
Z1
Recovery3%
Z2
Endurance26%
Z3
Tempo44%
Z4
Threshold13%
Z5
VO₂max14%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+1.2%
Effort & efficiency
0.71
Running effectiveness
speed per watt/kg, reps
6.4 w/kg
Power-to-weight
rep average
2.61
Efficiency factor
norm. power per bpm
1.07
Variability index
1.0 = perfectly even power
2.3%
Rep consistency
pace spread across reps, lower is tighter
3019 kJ
Total work
mechanical energy
1754 kcal
Energy
estimated burn
856 bpk
Cardiac cost
heartbeats per km
28%
Above threshold
≥ 164 bpm (Z4+)
-0:14/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace26°C · +210 m
Actual
3:40/km
Grade-adjusted
3:40/km
Heat-adjusted
3:30/km
−10s/km
True effort
3:30/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.