Optokinetic

Just read about chessboxing tournaments: A round of chess alternates with a round of boxing. Started in Germany.
It seems likely that some good shots to the head would interfere with one's concentration. As a psychologist, I delight in the way that chess lends itself to all kinds of mind games. I also enjoy the elegance of a good game -- win or lose. There is a parallel to boxing with deceptive feints preceding a crashing blow. I can't think of any game that is as beguiling as chess.