I think it's momentum. If you hit the ball while the paddle is moving it gets a thrill. Pretty nice if you know to handle it but very unfair on high speed when you opponent is using it. ;)
Ahh ok thx.
Btw "knowledge" is added over the days? I just got the message "This is the 60th did you know" but I have it running for 2 days now so it should be way more already. :(