*chucklin'*...I couldn't help chucklin' at this line by Vampy: "...like a knife cutting through hot butter."
If it was hot butter, pretty logical that the butter would be in liquid form...perhaps he simply had a typo here and meant to say:
'...like a hot knife cutting through butter....'
Just as it is with any sport, they are discovering more technical advances to achieve the greatest outcome! These shark skins is just another advantage in swimming...some or all of these Olympians' swimmers are known to shave every strand of hair on their bodies to achieve less resistance in the water...heck, I could achieve maxium resistance to the water
just by walkin' around the length of the pool!!