Whoever said anything about doing what Van Damme does in Kickboxer, shut the hell up, because you know nothing.
When you spar, wear shinguards. And You can't really ever stop the pain you get when you kick someones shin. Because think about it, your shin is like a baseball bat, that's why it hurts so much. Now imagine instead of a punch bag dangling from the ceiling, think of a baseball bat. Kick that and it'll hurt like hell.
That's why using your shin for defense is a good thing, cause it hurts your opponent