Intervalsconfidence 0.83
5 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
5 × 400m
Distance
24.3 km
Moving
120:24
Rep pace
3:27/km
Avg HR
149 bpm
Reps
5
Planned vs actual · TrainingPeaksPlanned 24.0 kmRan 2:00:24 · 24.3 kmIF 1.37TSS 377
Shape of the sessionEasyWorkFastest
warm up
cool down
0:005 × work / float120:24
The decode
Four 200m efforts and five 400m reps formed a combined speed-and-interval session. The short work prepared the faster 400m block without making the session a straight five-rep set.
The 400m reps accelerated through the third, dipped on the fourth, and finished faster than the first. Heart rate rose from 163 to 166 while the recoveries lengthened through the third rep before shortening for the fourth.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:31 | 3:39/km | 163 | 1:58 |
| 2 | 1:26 | 3:26/km | 164 | 2:02 |
| 3 | 1:18 | 3:11/km | 165 | 2:14 |
| 4 | 1:33 | 3:35/km | 164 | 1:59 |
| 5 | 1:28 | 3:23/km | 166 | 8:03 |
0.83
confidence
What the engine saw
- 5 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 195s.
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
Recovery22%
Z2
Endurance51%
Z3
Tempo17%
Z4
Threshold7%
Z5
VO₂max2%
Pace
Z1
Easy65%
Z2
Endurance27%
Z3
Tempo1%
Z4
Threshold2%
Z5
VO₂max0%
Z6
Speed5%
Power
Z1
Recovery4%
Z2
Endurance30%
Z3
Tempo54%
Z4
Threshold5%
Z5
VO₂max5%
Z6
Anaerobic1%
Z7
Neuro0%
Aerobic decoupling · Pa:HR-1.1%
Effort & efficiency
0.74
Running effectiveness
speed per watt/kg, reps
6.6 w/kg
Power-to-weight
rep average
2.54
Efficiency factor
norm. power per bpm
1.06
Variability index
1.0 = perfectly even power
4.7%
Rep consistency
pace spread across reps, lower is tighter
2975 kJ
Total work
mechanical energy
1755 kcal
Energy
estimated burn
853 bpk
Cardiac cost
heartbeats per km
10%
Above threshold
≥ 164 bpm (Z4+)
-0:04/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace16°C · +127 m
Actual
3:26/km
Grade-adjusted
3:26/km
Heat-adjusted
3:26/km
True effort
3:26/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.