The only things a user can do to get an accurate training effect is:
- wear a chest strap during all activities
- make sure your max HR is correct. The watch does a good job at estimating max HR through auto-detection if your are a runner or a biker and you workout across a variety of efforts from long easy to maximal effort interval repeats.
- wear your watch all day to ensure the rest HR is accurate over time.
Note that the watch will not give you a very accurate anaerobic training effect outside of running with good pace data, and cycling with good power data. I am not sure about swimming as I don't know whether the critical swim speed data point is used for anTE.
If you do rowing, climbing, crossfit, HIIT. Tabata, etc. with a chest strap, you will get accurate aerobic training effect, but the anaerobic effect, if any, will be underestimated. This is a limitation of the algorithm, model and available sensors.
If you wear the wrist HR only during these types of activities, the readings will be wrong, including any anaerobic effect the watch might end up reporting because the watch won't be able to read you HR accurately enough.
