I was watching the 06 China Masters MD between Xie & Guo versus Hopp & Kindervater and I was noticing that the Chinese players were giving hand signals to each other behind their backs! Download the video and you'll see they point out certain number of fingers to mean something.

I'm curious, does anyone know what they were communicating to each other? And does anyone out there also use them? Seems quite interesting :)

It shouldn't be something new...at least in other sports they do this, specifically volleyball and baseball. Since BAD is closer to volleyball, in volleyball they give hand signals on where to return the serve/how to set up the point, etc...

I'd guess in BAD, the returner was probably indicating where/how the serve was going to be returned so the partner can set-up for the shot.

Or something similar. :)

I've noticed a couple of other pairs that use hand signals:
Cai/Fu and Malaysian youngsters Ong/Tan.

I think it has to do with the serve. Singalling behind your back whether it will be a long serve, short serve, etc. This way, your partner can prepare for the serve without giving away any information beforehand.