2025 JPN JUNIOR LONG COURSE CHAMPIONSHIPS
- Saturday, May 11th & Sunday, May 12th
- Tokyo, Japan
- LCM (50m)
- Results
At the 2025 Japanese Junior Championships, held in Tokyo on May 11–12, 16-year-old Raito Numata delivered a remarkable performance in the boys’ 400 IM, clocking a time of 4:12.10. This swim not only secured him the gold medal but also established a new world best for boys aged 16 and under in this event.
Numata’s time ranks as the seventh-fastest globally in the 400 IM for the year. Leading the world rankings is fellow Japanese swimmer Tomoyuki Matsushita, who posted a 4:08.61 at the 2025 Japan National Swimming Championships in March.
Prior to Numata’s achievement, the fastest time recorded by a 16-year-old in this event was 4:12.44 by China’s Zhang Zhanshuo, who earned a silver medal at the 2023 World Junior Championships. Notably, Matsushita won that race, then aged 18.
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The all-time top 10 performers in the 400m IM for boys aged 16 and under include several notable swimmers:
- Kosuke Hagino (Japan): 2016 Olympic champion, recorded 4:14.58 at the 2011 Japan Open.
- Carson Foster (USA): 2024 Olympic silver medalist and current U.S. National Age Group record holder for 15–16-year-old boys (4:14.73).
- Daiya Seto (Japan): Former world champion and 2016 Olympic bronze medalist.
- Ilia Borodin (Russia): Former world junior record holder.
For context, here are the best 400m IM times achieved by recent Olympic champions when they were 16:
Michael Phelps (USA): 2004 and 2008 Olympic champion, swam 4:15.20 at the 2001 Spring Nationals, marking the second-fastest U.S. performance ever for 16-year-old boys, only behind Carson Foster. Phelps broke the world record in 2002 with a time of 4:11.09 shortly after turning 17.
Ryan Lochte (USA): 2012 Olympic champion; there is no record of him competing in the 400 IM at age 16. At 18, he had yet to break the 4:20 barrier.
Kosuke Hagino (Japan): 2016 Olympic champion, recorded 4:14.58 at the 2011 Japan Open. He went on to win a silver medal at the 2012 London Olympics the following year.
Chase Kalisz (USA): 2021 Olympic champion, posted a time of 4:26.97 at the 2010 U.S. Junior National Championships at age 16, which does not place him among the top 100 fastest U.S. performers for 15–16-year-old boys.
Leon Marchand (France): 2024 Olympic champion, swam 4:19.41 at the French Championships in April 2019, just before turning 17. Later that year, at age 17, he improved to 4:16.37 to win bronze at the 2019 World Junior Championships, setting a new French national record at the time.
Notably, swimmers like Hagino, Seto, Foster, and Borodin, who posted impressive times at age 16, have gone on to achieve significant international success. It will be exciting to see how Numata’s career unfolds in the coming years.
It seems to me that Asian male swimmers peak earlier. Could it be related to reaching physical maturity earlier? It also could be that they have better technique at a younger age. American/European swimmers on the other hand improve a lot in college swimming.