Intervalsconfidence 0.83
5 × 400m
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
5 × 400m
Distance
10.0 km
Moving
45:41
Rep pace
3:34/km
Avg HR
158 bpm
Reps
5
Shape of the sessionEasyWorkFastest
warm up
cool down
0:005 × work / float45:41
The decode
Five 90-second repetitions made this a compact, repeatable speed set, with 90-second recoveries establishing a controlled rhythm.
The opening 3:40/km rep gave way to 3:32/km for reps two and three, then 3:34/km for the final two. Heart rate rose from 159 to 174 by the third rep and stayed at 173 and 171 thereafter, so the pace held while the response peaked mid-set.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:30 | 3:40/km | 159 | 1:30 |
| 2 | 1:30 | 3:32/km | 167 | 1:30 |
| 3 | 1:30 | 3:32/km | 174 | 1:30 |
| 4 | 1:30 | 3:34/km | 173 | 1:30 |
| 5 | 1:30 | 3:34/km | 171 | 0:12 |
0.83
confidence
What the engine saw
- 5 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 74s.
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
Recovery6%
Z2
Endurance25%
Z3
Tempo43%
Z4
Threshold17%
Z5
VO₂max9%
Pace
Z1
Easy64%
Z2
Endurance19%
Z3
Tempo10%
Z4
Threshold7%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance10%
Z3
Tempo67%
Z4
Threshold22%
Z5
VO₂max1%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR-4.4%
Effort & efficiency
0.79
Running effectiveness
speed per watt/kg, reps
5.9 w/kg
Power-to-weight
rep average
2.54
Efficiency factor
norm. power per bpm
1.01
Variability index
1.0 = perfectly even power
1.4%
Rep consistency
pace spread across reps, lower is tighter
1207 kJ
Total work
mechanical energy
702 kcal
Energy
estimated burn
805 bpk
Cardiac cost
heartbeats per km
26%
Above threshold
≥ 164 bpm (Z4+)
-0:30/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace25°C · +56 m
Actual
3:34/km
Grade-adjusted
3:34/km
Heat-adjusted
3:26/km
−8s/km
True effort
3:26/km
−8s/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.