Swamped

Whoever tied you up was either in a hurry or severely untrained. There's a good half-inch of slack around your hands, more than enough to wriggle one loose.

Unfortunately, the ropes around your body, including your upper arms, are considerably tighter. And you can't seem to reach the back of the post with just your free forearm. Despite the rush job, this is uncomfortably difficult to get out of, though you make a good effort of it.

You finally manage to loosen the main knot and slip out just as the wagon suddenly stops.

Now what do you do?