Breaking news: Olympic swimmers pee in the pool. A lot. From a former USA national team member:
Before a race is an interesting time. It depends on the meet and to some extent the color of the pool deck. I kid you not. You always try to pee before you swim, but sometimes your body defies logic and finds a way to refill your bladder just to spite you. Adrenaline and nerves wreak havoc on your system, and I knew tons of other swimmers that always, regardless of prior planning, had to pee right before a race. What to do if you’re desperate?
Read the whole thing here.