I live at 1,000 feet and trained on the river bluffs. My son and I went up and down the bluffs with full packs. The climbs were not much but it is all we have close by. Most climbs are 200 to 300 feet. But, doing that with full packs in the humid summer really did the trick. We could not replicate the altitude obviously, but it seems that at least under 9,000 or so feet humidity is a wash with altitude.