Have you wondered

I would

Yes.

Asking the real questions

My niece peed in an ex commonwealth games pool a few years back (she was3)

I'm pretty sure Michael Phelps or the other new guy (Ryan or something I think?) admitted to doing this

swimmers pee in their suits to keep them warm

how do you pee when your racing?

That's the first thing I would do.

Yea

Locte admitted to it