I’ve been reading about zone 2 and have been adding it to my training. I use a stair climber as it’s easy to control for variables. I’m 48 and my heart rate is 125-130. It’s an easy pace I can maintain for a long time time, feels like an all day pace, and I can breath through my nose and talk easily. Does this sound like zone 2? I’m surprised my heart rate is that high. When I ruck with 45lbs on flat ground my heart rate is 103