Yes, backpacking is exercise but.... I've heard PCT hikers lament how wasted they get especially their upper bodies. A week into a 4-5 week walk I'm already feeling this. Ski season is just around the corner. I ran yesterday and did some agility drills. Very sluggish. After walking all day, I tend to be unmotivated to do any maintenance conditioning. Even stretch. Had to do some scrambling and use some fixed ropes a couple times -- felt so good after just walking.
Directed at winter athletes, triathletes, etc. Do you supplement your walking with on trail conditioning of some sort?