[jraines]

the backstroke rule change was circa 1988. They changed butterfly (and I suppose freestyle) after the 96 Olympics when Dennis Pankratov won both butterflies with this technique. Interestingly, the backstroke innovator who probably triggered the earlier rule change got beat in the final by someone not using it (Berkhoff in 88, silver)

The latest rule change in this area was banning dolphin kicks on your back on the breast-to-free exchange in IM. Ryan Lochte triggered that one.

[onlypassingthru]

According to the article it was 1998...

"That all changed in 1998, when FINA, the world governing body of competitive swimming, ruled that swimmers performing the backstroke had to surface after 15 meters."

... which aligns with my recollection of the '96 Olympics and being gobsmacked at how long the swimmers were holding their breath.

[jraines]

The article is wrong. That’s when they changed it for fly/free.

Here is the 92 backstroke final. The announcers mention the rule: https://youtu.be/FTfTyzkSzQs?si=E82rvKql-w9vuwSf

I tried to find 96 and cannot but it was the same.

Here is the butterfly performance in 96 that ultimately triggered them to chamge it for fly/free: https://youtu.be/Zp2NTFjeXQQ?si=e_E-D1ZAvzNmjACe

[xarope]

They would swim the entire 50m underwater, if given the chance. I've seen them do so in practice, very lazy-looking dolphin kicks, but still faster than most swimmers on the surface.