Intervalsconfidence 0.88
4 x 1k
Colin Dismuke50 km / marathon build
Source: own Strava export
Intervals
4 x 1k
Distance
8.5 km
Moving
36:11
Rep pace
3:42/km
Avg HR
168 bpm
Reps
5
Shape of the sessionEasyWorkFastest
warm up
cool down
0:005 × work / float36:11
The decode
A kilometre-rep set with a descending finish extended the work beyond the main repeats, making the session a progressive speed-endurance effort rather than a clean repeat set.
The four 1km reps slowed from 3:34/km to 3:47/km, while the final 600m held 3:42/km. Heart rate rose from 165 to 176 across the main work and reached 181 during the later cooldowns.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 3:34 | 3:34/km | 165 | 1:15 |
| 2 | 3:43 | 3:43/km | 170 | 1:15 |
| 3 | 3:45 | 3:45/km | 174 | 1:15 |
| 4 | 3:47 | 3:47/km | 175 | 1:15 |
| 5 | 2:13 | 3:42/km | 176 | 1:00 |
0.88
confidence
What the engine saw
- 5 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 72s.
- Matches the athlete's own session label.
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
Recovery3%
Z2
Endurance14%
Z3
Tempo10%
Z4
Threshold43%
Z5
VO₂max31%
Pace
Z1
Easy39%
Z2
Endurance8%
Z3
Tempo37%
Z4
Threshold15%
Z5
VO₂max1%
Z6
Speed1%
Power
Z1
Recovery0%
Z2
Endurance17%
Z3
Tempo29%
Z4
Threshold31%
Z5
VO₂max23%
Z6
Anaerobic1%
Z7
Neuro0%
Aerobic decoupling · Pa:HR+7%
Effort & efficiency
0.72
Running effectiveness
speed per watt/kg, reps
6.3 w/kg
Power-to-weight
rep average
2.60
Efficiency factor
norm. power per bpm
1.03
Variability index
1.0 = perfectly even power
2.0%
Rep consistency
pace spread across reps, lower is tighter
921 kJ
Total work
mechanical energy
588 kcal
Energy
estimated burn
714 bpk
Cardiac cost
heartbeats per km
74%
Above threshold
≥ 164 bpm (Z4+)
-0:04/km
Split balance
negative split, faster 2nd half
Conditions-adjusted pace24°C · +18 m
Actual
3:42/km
Grade-adjusted
3:42/km
Heat-adjusted
3:34/km
−8s/km
True effort
3:34/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.