Heart-in-the-mouth feeling whilst asleep? is it normal?

I've never found anybody else who has experienced this sensation, but I thought I'd put it out there in case one of you guys has. When I was a child, I would dream about walking or running, but every step I took went really far: it wasn't just a dream though, there was a physical feeling accompanying it. When I dreamed I was up in the air, mid-giant-step as it were, I got a feeling as though my heart was in my mouth, like you get on those rocking pirate-ships in theme parks. When I landed, there was a definite feeling of impact on my shins. It wasn't scary, but very odd, and although I've found many people who have experienced the sensation of tripping in their sleep and waking themselves up by kicking, I have never found a person who has felt this. It happens less frequently nowadays, but I still really want to know just what an earth it can be? Thanks for your help, I've been on a quest to find the answer to this for years!!