I've watched a guy rattle off consecutive 400m runs at right around a minute for college football conditioning. Big deal, right? He was 6'6 and 260 lbs, and we seldom ran 400s.

As for furniture movers, the one crew I watched had a couple of average size Samoans, and one guy who went about 6'4 and 275. He could do about double what either of the other two could.

The "I smoked a collegiate linebacker while hunting" stories on here are never not entertaining, along with excuses made to not get strong. Why wouldn't you train to where all your heavy backpacking motions were sub-maximal to the point of not even causing soreness the next day?