@sky-runner Treadmill session this morning: 2 × 5 minutes at 12 km/h, with 14 minutes of warm‑up at 8 km/h before the first acceleration, 2 minutes at 8 km/h between the two fast intervals, and 2 minutes of walking at 6 km/h to make a total of 28 minutes.
First issue: the Suunto Race 2 couldn’t connect to the Polar H10. So I used the Garmin HRM 200 chest strap instead, and that worked fine. Clearly, pairing problems with chest straps still aren’t fully solved.
Zone Sense results: aerobic–anaerobic thresholds at 150 and 153 bpm, which doesn’t make sense. The 150 bpm aerobic threshold is consistent with Garmin’s zones. During the fast intervals I was in Zone 3, slightly below my lactate threshold. I think that’s why Zone Sense didn’t estimate the second threshold correctly — you need to go above it.
Conclusion: the first threshold is correct. Too bad that if I do an easy Zone 2 session tomorrow, it will probably calculate a second threshold that’s far too low.