Running

Hello,

I'm confused about low heart rate training Zone and which zone is meant with it. My 23 heart rate zone ends at 130bpm. When running in that zone it is very relaxed. According to the MAF formula my low heart rate zone ends at 142bpm. This is in the upper part of Z3 aerobic Zone. That BPM is don't consider low heart rate when running.

Isn't "low heart rate zone training" done at Z2? Or am I missing something?

To make it even more confusing, my Garmin watch suggest to do base training with a 138bpm HR which is another value. Which zone makes most sense to use for my base runs and why?