In freestyle swimming, 50% of the propulsion in the water comes from the kicking movements. Therefore, swimmers need to constantly practice various kicking movements both on land and in the water. I also incorporate underwater training into my training (for example, swimming underwater using only kicking movements, with or without fins, or simulating freestyle kicking movements underwater (done while holding your breath with your arms straight against the side of the pool). #freestyle #freestyle

Ranomi Kromowidjojo Wins Women's 50m Freestyle Gold - London 2012 Olympics