Intervalsconfidence 0.83
Zones are a number: 158
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
Zones are a number: 158
Distance
14.1 km
Moving
64:31
Rep pace
2:59/km
Avg HR
154 bpm
Reps
5
Planned vs actual · TrainingPeaksPlanned 1:02:46 · 14.0 kmRan 1:04:31 · 14.1 kmIF 1.29TSS 177
Shape of the sessionEasyWorkFastest
warm up
cool down
0:005 × work / float64:31
The decode
This was a tempo session centred on 8,000 m at 4:27/km. The sustained block made it a tempo effort rather than a collection of isolated sprints. The short accelerations came after that load, layering speed onto an already elevated aerobic cost.
The main block sat at 4:27/km with HR 158, close to the stated 4:25/km tempo target. The accelerations peaked at 2:45/km and closed at 3:00/km; HR ended at 173 after reaching 171 on the preceding interval.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 0:14 | 3:13/km | 166 | 0:36 |
| 2 | 0:16 | 3:05/km | 168 | 0:37 |
| 3 | 0:16 | 2:45/km | 163 | 0:51 |
| 4 | 0:16 | 2:50/km | 171 | 0:50 |
| 5 | 0:16 | 3:00/km | 173 | 2:32 |
0.83
confidence
What the engine saw
- 5 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 65s.
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
Recovery24%
Z2
Endurance11%
Z3
Tempo53%
Z4
Threshold9%
Z5
VO₂max2%
Pace
Z1
Easy29%
Z2
Endurance66%
Z3
Tempo3%
Z4
Threshold0%
Z5
VO₂max0%
Z6
Speed1%
Power
Z1
Recovery1%
Z2
Endurance12%
Z3
Tempo64%
Z4
Threshold21%
Z5
VO₂max1%
Z6
Anaerobic1%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+2.5%
Effort & efficiency
0.90
Running effectiveness
speed per watt/kg, reps
6.3 w/kg
Power-to-weight
rep average
2.55
Efficiency factor
norm. power per bpm
1.01
Variability index
1.0 = perfectly even power
5.7%
Rep consistency
pace spread across reps, lower is tighter
1544 kJ
Total work
mechanical energy
991 kcal
Energy
estimated burn
725 bpk
Cardiac cost
heartbeats per km
11%
Above threshold
≥ 164 bpm (Z4+)
-0:20/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace26°C · +41 m
Actual
2:58/km
Grade-adjusted
2:58/km
Heat-adjusted
2:50/km
−8s/km
True effort
2:50/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.