10 × 400m
Source: own Strava export
A threshold-and-VO2 session combined a progression, threshold running and two blocks of faster 400 m repetitions. Static recoveries made each repetition a discrete speed demand, while the threshold work placed that speed under accumulated fatigue.
The first block moved from 1:21 to 1:25, and the second ran 1:25, 1:23, 1:23, 1:24 and 1:22. Heart rate sat at 169-175 in the first block and 169-173 in the second, while the intervening 2 km threshold segment reached 180. The slower middle did not become a fade; the closing 400 m was 1:22.
Rep splits
| Rep | Time | Pace | HR | Float |
|---|---|---|---|---|
| 1 | 1:21 | 3:22/km | 175 | 0:45 |
| 2 | 1:23 | 3:27/km | 171 | 0:45 |
| 3 | 1:22 | 3:24/km | 170 | 0:45 |
| 4 | 1:22 | 3:24/km | 171 | 0:45 |
| 5 | 1:25 | 3:33/km | 172 | 0:45 |
| 6 | 1:25 | 3:32/km | 169 | 0:45 |
| 7 | 1:23 | 3:27/km | 170 | 0:45 |
| 8 | 1:23 | 3:27/km | 173 | 0:45 |
| 9 | 1:24 | 3:30/km | 173 | 0:45 |
| 10 | 1:22 | 3:24/km | 173 | 0:45 |
What the engine saw
- 10 work intervals detected from lap markers, confirmed by clear pace separation.
- Recoveries average 45s.
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.