Women's 400M Freestyle heats at Rio 2016 Olympics

America's Katie Ledecky competes in heat four of the Women's 400M Freestyle at the Olympic Aquatics Stadium at the 2016 Rio Summer Olympics in Rio de Janeiro, Brazil, on August 7, 2016. Ledecky won her heat with an Olympic record time of 3:58.71. Photo by Matthew Healey/UPI