Some 8 years ago, a wise man at the Olympiastützpunkt Hamburg told us students, that he expected the underwater dolphin kicks in backstroke to be where the biggest performance improvements would be made in swimming technique the coming years.
Watch this video from the 200 backstroke final in Manchester this weekend, and notice how equal the two leading swimmers are, until Rogan (yellow cap) stays underwater just that little bit more after the last turn, that makes the difference between a world record and number two.