Intervalsconfidence 0.83
4 × 4min
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 × 4min
Distance
13.5 km
Moving
66:11
Rep pace
3:53/km
Avg HR
148 bpm
Reps
4
Shape of the sessionEasyWorkFastest
warm up
cool down
0:004 × work / float66:11
The decode
Four work intervals formed a rep session. Recoveries ranged from 4 seconds to 242 seconds, making the load uneven rather than a consistent repeat set.
The work pace moved from 3:52/km to 4:00/km to 3:55/km, then 3:46/km, with the fastest effort last. Heart rate moved from 163 to 147 to 140, then 151, so the set showed no progressive cardiovascular rise.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 3:52 | 3:52/km | 163 | 0:04 |
| 2 | 3:27 | 4:00/km | 147 | 1:47 |
| 3 | 3:55 | 3:55/km | 140 | 1:59 |
| 4 | 3:46 | 3:46/km | 151 | 4:02 |
0.83
confidence
What the engine saw
- 4 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 118s.
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
Recovery27%
Z2
Endurance23%
Z3
Tempo45%
Z4
Threshold5%
Z5
VO₂max0%
Pace
Z1
Easy44%
Z2
Endurance30%
Z3
Tempo25%
Z4
Threshold2%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery10%
Z2
Endurance26%
Z3
Tempo29%
Z4
Threshold34%
Z5
VO₂max0%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR-12%
Effort & efficiency
0.74
Running effectiveness
speed per watt/kg, reps
5.8 w/kg
Power-to-weight
rep average
2.67
Efficiency factor
norm. power per bpm
1.09
Variability index
1.0 = perfectly even power
2.2%
Rep consistency
pace spread across reps, lower is tighter
1675 kJ
Total work
mechanical energy
946 kcal
Energy
estimated burn
845 bpk
Cardiac cost
heartbeats per km
5%
Above threshold
≥ 164 bpm (Z4+)
-0:13/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace19°C · +93 m
Actual
3:53/km
Grade-adjusted
3:53/km
Heat-adjusted
3:49/km
−4s/km
True effort
3:49/km
−4s/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.