EDIT: Nevermind, I just had some bad information.

I'm not sure if I'm slower or not, but sprinting in heavy armor seems to consume fatigue more quickly.

Hmm, I'll test that out. I'd been meaning to streak through town, anyway.

I never read heavy armor would make you run slower, only that it would take more fatigue for sprint.

i can confirm that it makes u slower iron doesn't slow u so much tho but try wearing dwarven armor and u will notice