5 × 400m
Source: own Strava export
Five 90-second VO2 repetitions off 60-second recoveries formed the speed block. The headwind made the work more demanding, while the short recoveries kept it from becoming a sequence of isolated sprints. The session then shifted into longer work and closed at goal race pace, testing whether the speed could be carried into sustained running.
The repetitions held a narrow 3:23/km to 3:28/km range, with heart rate rising from 173 to 183. The final rep was the slowest, but the set remained controlled; the later work reached 3:31/km and 3:32/km before the 8-minute finish at 3:49/km with HR 182.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:30 | 3:24/km | 173 | 1:00 |
| 2 | 1:30 | 3:25/km | 177 | 1:00 |
| 3 | 1:30 | 3:23/km | 179 | 1:00 |
| 4 | 1:30 | 3:25/km | 177 | 1:00 |
| 5 | 1:30 | 3:28/km | 183 | 1:00 |
What the engine saw
- 5 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 60s.
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. The gap between actual and true effort is the day's hidden work: conditions were taxing the clock.