Sorry for the misunderstanding. That’s my fault. You can run/hike on a treadmill for any of these aerobic base workouts. Vary the grade of the treadmill from time to time.
In the plan some say run/hike hilly terrain with no mention of a treadmill, some have the option of a treadmill. Does this mean only some runs/hikes can be done on a treadmill? and others must be done outside? or can all be adapted for treadmill use?