FWIW:
I "created" a calculator to
approximate the workload of a hike - relative to the work to walk one flat mile. It's based on data taken from research paper by Minetti on treadmill work, so there are certainly some assumptions.
Keep in mind, this approximates Work / Energy required - not any sort of limit to rate of energy production as there would be at altitude (something fun to add in the future).
I don't know what the exact stats of the Whitney ascent are, but let's say 11 miles, 6500 ft gain. Equivalent number of flat miles is ~ 23.
23 is less than 26.2, and I would say from experience that if Whitney was at lower altitude, it would certainly be easier (assuming constant exertion).
As altitude increases, the sustainable rate of work will decrease (more anaerobic work). This will vary from person to person depending on genetics, altitude exposure, etc... For instance maintaining a 170 bpm heartrate at 13,000 ft could output 1/2 the power (or vertical ascent rate) of 170 bpm at sea level. Both will feel as intense.
In my case, attempting to sustain a marathon heartrate up Whitney may perhaps come close to a marathon time for me, but probably a bit slower. However, my brain would likely explode, so I would say it's harder.
