What kind of surface do you train on?

[tufrthanu]

Wire, I see those jigsaw mats on tv at the NASKA tourneys a lot. It makes me wonder how they don't have lots of sprains and things. Especially with some of the more exotic forms competitions they have going. I often wondered how sweat was handled on a wooden dojo floor. Besides the slippage I would think the floor would need to be cleaned every day? to prevent warping or discoloration?