I purchased the 16 weeks big mountain plan and I am in week 2. In the description of the “zone 2 hike on hilly terrain” workouts, the notes are stating that the total time should include both ascent and descent, if the workout is outdoor, whereas only ascent if performed on gym machines. I find it hard to maintain however my HR in zone 2 when hiking downhill. Inevitable, HR goes down to 100bpm, whereas my AeT is 130bpm.

Is that fine anyway or should HR be in Zone 2 even for the downhill portion, which I find hard to achieve without running fast downhill (I cannot do it, too hard on my joints)? If the HR can go below Zone 2 on an outdoor course, wouldn’t the gym workout have a much heavier training load?