I do not know if this makes sense, but I am incorporating zone 2 training so that I do not train only in high intensity zones. To make zone 2 training a bit more relevant I am trying to do it with KB, so it mainly involves doing a few reps and then waiting to control the HR, the heavier the bell the harder it gets. In my last attempt I started with double and single 12kg and then went up to 28kg doing mainly clean and press, jerk or press. I need to keep track of the reps and maybe not go above 16kg. I wonder if short peaks above the threshold make a big difference. I am tracking my HR with a chest strap.