I was just reviewing some elevation profile from the Inca trail that I did last year:
On the 2nd day we started at Wayllabamba and ended around Chaquicocha.
Around 6000 ft gain. A large portion of those were steps, easily over 1000 ft gain per mile. Most of it was above 10,000 ft. While carrying a 40 lb backpack.
Upon review, it was pretty hard.