Swimming's governing body voted Friday to include two different mixed-gender relays — the 4x100-meter freestyle and the 4x100 medley — at future world championships.
Teams will be made up of two men and two women, and it is up to them to decide the order. So, for instance, a woman could race against a man on the anchor leg.
Having already been tested at a World Cup meet in Dubai last year, the mixed relays will get their official debut at the 2014 short-course worlds in Doha, Qatar, in the 4x50 format. Then they will make their long-course worlds debut in 2015 in Kazan, Russia.
The mixed relays have not been approved for the Olympics.