The World Aquatics Junior Swimming Championships is an international swimming championship event organized biennially by World Aquatics for swimmers aged 14–18 years as of the 31st December of the year of the competition. It is usually held on odd years. Prior to 2023, the event was known as the FINA World Junior Swimming Championships and was open to female swimmers aged 14–17 and male swimmers aged 15–18 as of the 31st of December of the year of the competition.
This article includes the world record progression for the 4×100 metres medley relay, and it shows the chronological history of world record times in that competitive swimming event. The 4×100 metres medley relay is a medley race in which each of four swimmers on a team swims a 100-metre leg of the relay, each swimming a different stroke, in the following sequence:
- Backstroke ;
- Breaststroke;
- Butterfly;
- Freestyle.
The heats for the men's 50 metre freestyle race at the 2009 World Championships took place on 31 July and 1 August 2009 (final) at the Foro Italico in Rome, Italy.
The men's 200 freestyle at the 11th FINA World Aquatics Championships swam 25+26 July 2005 in the Olympic pool at Parc Jean-Drapeau in Montreal, Canada. 95 swimmers were entered in the preliminary heats, which swam in the morning of July 25. The top-16 swimmers from the prelims advanced on to semifinal heats that evening. From the semifinals, the top 8 swimmers advanced onto the next night's final.
The men's 200-metre butterfly event at the 2001 World Aquatics Championships took place between 23 July – 24 July. Both the heats and semifinals were held on 23 July with the heats being held in the morning session and the semifinals being held in the evening session. The final was held on 24 July.
The men's 50 metre freestyle event at the 2001 World Aquatics Championships was held on 22 and 23 July 2001 (final) at the Fukuoka, Japan.
The men's 100 metre freestyle event at the 2001 World Aquatics Championships took place 27 July. The heats and semifinals were held on 26 July.
The men's 50 metre backstroke event at the 2001 World Aquatics Championships took place 25 July. The heats and semifinals took place 24 July, with the final being held on 25 July.
The men's 50 metre butterfly event in swimming at the 2013 World Aquatics Championships took place on 28–29 July at the Palau Sant Jordi in Barcelona, Spain.
Nicolas Fink is an American five-time world champion in breaststroke events. He is a world record holder in the short course 4×100 meter medley relay and 4×50 meter mixed medley relay. He is the Americas record holder in the short course 50 meter breaststroke, 100 meter breaststroke, and 200 meter breaststroke as well as the American record holder in the long course 50 meter breaststroke. In the 50 meter breaststroke, he won the World Short Course titles in 2021 and 2022 and World Long Course title in 2022. In the 100 meter breaststroke, he is the 2022 World Short Course gold medalist. In the 200 meter breaststroke, he is the 2021 World Short Course gold medalist.
The women's 100 metre breaststroke event at the 2020 Summer Olympics was held from 25 July to 27 July 2021 at the Tokyo Aquatics Centre. It was the event's fourteenth consecutive appearance, having been held at every edition since 1968.
The women's 200 metre butterfly event at the 2020 Summer Olympics was held from 27 to 29 July 2021 at the Tokyo Aquatics Centre. It was the event's fourteenth consecutive appearance, having been held at every edition since 1968.
The women's 100 metre freestyle competition of the 2018 FINA World Swimming Championships was held on 12 and 13 December 2018.
The women's 100 metre freestyle event at the 2001 World Aquatics Championships took place 25 July. The heats and semifinals were held on 24 July.
The men's 50 metre breaststroke event at the 2001 World Aquatics Championships took place 29 July. The heats and semifinals took place 28 July, with the final being held on 29 July.
The women's 100 metre breaststroke event at the 2001 World Aquatics Championships took place 23 July. The heats and semifinals took place 22 July, with the final being held on 23 July.
The women's 100 metre butterfly event at the 2001 World Aquatics Championships took place 28 July. The heats and semifinals took place 27 July, with the final being held on 28 July.
