I have never really thought of this before. A post talking about using the bathroom in a lucid dream sparked this thought.
I have held a conversation with someone while lucid. So that tells me there is some control.
We do often mumble in our sleep. BUT we do also, at times twitch and flinch and move our bodies.

So.... If we our in a lucid dream and fully conscious of our actions within our dream, can we administer any control over our SP bodies?