Certain animations seem to have movement attributed to them. Taking out, or putting away your weapon for example, can stop movement in progress, or cause a sprint animation from a stationary stance.

The most reproducible instance of this I have found, is trying to interact with a ladder with a weapon out. The character tends to lurch forward violently, into a sprinting animation as they holster their weapon.
The result being an instant death if you are at the top of said ladder.