As it says in the Garmin blog:
„It’s vitally important to warm up well for at least 10 minutes before Tabata training. If you attempt a hardcore workout of this kind with cold muscles, it’s likely that you’ll suffer a muscle strain or other injury.“
https://www.garmin.com/en-US/blog/general/tabata-training/
it would make sense to introduce the option to add warm up (until lap button press) and cool down to the watch’s HIIT App menu for HIIT standard timers (such as Tabata, EMOM and AMRAP training). The only ways to do this currently are to either record warm up as separate activity or create the entire workout in garmin connect, which limits the usefulness of the hiit timers built into the HIIT App on the watch.
Some other apps on the watch support optional warm up and cool down (e.g. cardio app) and I don’t understand why not all activities simply have these options by default.
