Intervalsconfidence 0.83
3 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
3 × 400m
Distance
10.7 km
Moving
45:01
Rep pace
3:23/km
Avg HR
135 bpm
Reps
3
Planned vs actual · TrainingPeaksPlanned 53:12 · 12.6 kmRan 45:01 · 10.7 kmIF 1.50TSS 167
Shape of the sessionEasyWorkFastest
warm up
cool down
0:003 × work / float45:01
The decode
A mixed 200m–1km–400m interval set paired speed at the shorter race distance with controlled work at the longer one, demanding clean changes of gear rather than one continuous intensity.
The 1km block moved from 3:26/km through 3:32/km to 3:34/km, keeping the latter two reps inside the stated 3:30-3:35 range. The 400m finish held 1:21, 1:21 and 1:22 as HR rose from 144 to 147, so the speed work stayed together.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:21 | 3:23/km | 144 | 0:60 |
| 2 | 1:21 | 3:22/km | 145 | 2:04 |
| 3 | 1:22 | 3:25/km | 147 | 2:03 |
0.83
confidence
What the engine saw
- 3 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 102s.
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
Recovery62%
Z2
Endurance38%
Z3
Tempo0%
Z4
Threshold0%
Z5
VO₂max0%
Pace
Z1
Easy57%
Z2
Endurance12%
Z3
Tempo3%
Z4
Threshold15%
Z5
VO₂max12%
Z6
Speed2%
Power
Z1
Recovery1%
Z2
Endurance28%
Z3
Tempo39%
Z4
Threshold21%
Z5
VO₂max10%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+3.6%
Effort & efficiency
0.81
Running effectiveness
speed per watt/kg, reps
6.0 w/kg
Power-to-weight
rep average
3.06
Efficiency factor
norm. power per bpm
1.04
Variability index
1.0 = perfectly even power
0.8%
Rep consistency
pace spread across reps, lower is tighter
1243 kJ
Total work
mechanical energy
619 kcal
Energy
estimated burn
667 bpk
Cardiac cost
heartbeats per km
0%
Above threshold
≥ 164 bpm (Z4+)
-0:28/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace23°C · +14 m
Actual
3:23/km
Grade-adjusted
3:23/km
Heat-adjusted
3:17/km
−6s/km
True effort
3:17/km
−6s/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.