Time to fix Gandalf versus the Witchking

[Sauron the White]

from Galendor

Sauron the White - regarding the glycogen use issue in the runner's muscles, if this is a concern then how do we explain Shadowfax? This horse ran at incredible speeds for very long distances, far beyond the ability of any "normal" horse. This isn't physiologically possible in the real world. If an argument is made that Gimli could not sustain his long run, then wouldn't the same argument apply to Shadowfax's performance? If not, why?

Shadowfax is described as one of the mearas - horses of the gods. It was said that Orome brought the first meara to Middle-earth direct from Valinor. I believe that puts him in a far different class than a mere dwarf.