4km tempo
Source: own Strava export
A half-marathon simulation with a 5 km build and 1 km recoveries was a controlled progression into descending goal-pace blocks. The build required pace to increase each kilometre before the longer work, while the easy recoveries separated the efforts without removing the session's sustained demand.
The 4 km and 3 km blocks both held 3:46/km, the 2 km block moved to 3:45/km, and the final 1 km reached 3:39/km. Heart rate stayed between 155 and 164 across those blocks, with the fastest running saved for the finish.
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
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.