Tempoconfidence 0.75
4km tempo
Colin Dismuke50 km / marathon build
Source: own Strava export
Tempo
4km tempo
Distance
11.8 km
Moving
50:24
Avg HR
146 bpm
Planned vs actual · TrainingPeaksPlanned 1:05:49 · 14.0 kmRan 50:24 · 11.8 kmIF 1.42TSS 166
Shape of the sessionEasyWorkFastest
0:00session50:24
The decode
A 4km tempo session used two sustained blocks. The 1km easy reset separated the efforts, making the second block a controlled progression rather than a single uninterrupted run.
Execution improved across the work: the second 4km block was faster at 4:00/km than the first at 4:06/km, while recorded heart rate fell from 158 to 140.
0.75
confidence
What the engine saw
- A sustained elevated-effort block with controlled pace variation.
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
Recovery38%
Z2
Endurance24%
Z3
Tempo32%
Z4
Threshold5%
Z5
VO₂max0%
Pace
Z1
Easy18%
Z2
Endurance39%
Z3
Tempo43%
Z4
Threshold0%
Z5
VO₂max0%
Z6
Speed0%
Power
Z1
Recovery0%
Z2
Endurance12%
Z3
Tempo43%
Z4
Threshold33%
Z5
VO₂max11%
Z6
Anaerobic0%
Z7
Neuro0%
Aerobic decoupling · Pa:HR-9.1%
Effort & efficiency
0.71
Running effectiveness
speed per watt/kg, reps
5.2 w/kg
Power-to-weight
rep average
2.95
Efficiency factor
norm. power per bpm
1.02
Variability index
1.0 = perfectly even power
8.6%
Rep consistency
pace spread across reps, lower is tighter
1325 kJ
Total work
mechanical energy
769 kcal
Energy
estimated burn
651 bpk
Cardiac cost
heartbeats per km
5%
Above threshold
≥ 164 bpm (Z4+)
-0:12/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace23°C · +24 m
Actual
4:27/km
Grade-adjusted
4:27/km
Heat-adjusted
4:19/km
−8s/km
True effort
4:19/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.