Weird VO2max

First suspect for an incorrect VO2 Max is your HR Max. Turn off auto-detection (because it is still subject to errors, despite improvements in the algorithm). Do a field test for your HR Max, if your doctor lets you. Also, make sure you weight and age are correct.

Second suspect is bad HR or pace data. Always use a chest strap for running and cycling activities, Choose the best GPS setting and make sure your powermeter is set up correctly for accuracy.

Third, make sure you do supra-thresholds workouts and maximal effort workout. A typical workout is maybe 85% of the maximal pace or power you can sustain steadily for that interval. Push yourself to replace your workout target with maximal effort to continue raising your power duration curve or pace duration curve.

Finally, the accuracy is much better on flat to moderatelye hilly grouns. Turn off VO2 Max detection for trail running.

It can take a few weeks for abnormal data to decay.

A couple of good cross-checking tips for verify that your watch has the right data:

- threshold. Do a threshold test, use threshold zones, and verify that your HR get in the right zones for the various pace-based or power-based workouts,

- race predictions. Check that the 5k, 10k, etc. predictions are showing an ambitious but realistic pace.

- stamina curve. When you do a base or tempo workout, the actual stamina should not drop from the potential stamina. For threshold workouts, it should barely hang in there, or drop a little. For VO2 Max, it should drop during the intervals, but resting periods should bring back to potential. For anaerobic workouts, the last intervals should bring the stamina to the floor, but not lower (not flattening of the curve at the bottom).