LOL! I had to look that up:

Next Cetojevic gave Djokovic a slice of bread. He told the bemused player not to eat it but to hold it against his stomach with his left hand while he again pushed down on his outstretched right arm. To Djokovic’s astonishment, the arm felt appreciably weaker.

I don't know about that... What, is the bread sending instant signals to his brain? That sounds like a load of BS. I'd like to see the science behind that. haha! If that is true I will virtually eat this post.