I think they are referring to this: https://winwenger.com/books/books-online/two-guaranteed-ways...

"For accumulating 20 hours of held-breath underwater swimming within 3 weeks from start to finish– 10 or more points I.Q. gain; better span of attention; better span of awareness; better awareness of the interrelatedness of things and of ideas and/or perceptions; finding yourself way better at winning arguments or disputes!"

It should go without saying this is nonsense.