Not on auto-run, this is when I decide to run - not sprint - my Orc appears to be in the sprint animation. That is - not the normal run animation.
I removed all skill points, all champion points and all gear, and yet it persists.
Edit: for clarity.
The only difference between normal running and sprinting is the speed at which my character moves.
ie: if I only depress the w key (forward momentum) My Orc runs with the sprint (shift w) animation.
Only other thing I can think of that alters the way your character behaves, is that you have a "Personality" toggled on. (i.e Thief, Assassin, Dutchess etc). Tough to get an idea of your problem without a moving picture.
Do you have a video showing your character walking / running / sprinting?