Please knock

My gym. Ugh.

I frequent an express version of my gym. Meaning it has less equipment and classes, no locker rooms and that, despite its name, it isn't actually open 24 hours a day. I am not sure how much longer I can grin and bear it. But, I don't know what other options are practical, especially in the financial department.
So this morning I went to the gym. I went to use the restroom before I got going (a last ditch procrastination effort...). There are four individual bathrooms in one hallway. I appreciate the individual part-- I've never been a fan of stalls. The doors have locks on them which is really good because instead of knocking on a closed door, people just wail on the handle and jiggle it furiously until they piece together that that particular bathroom is occupied.
I have a nervous bladder. If I know someone can hear me pee, I freeze up no matter how badly I have to go. This condition has taken on a new twist while at the gym. I am so terrified of two situations:
1) I forget to lock the door
2) The handle breaks (which judging by how aggressively some patrons open doors is bound to happen sooner than later).
So now, even though no one can hear me go, I get stage fright. I know that the second I let loose, some meat head is going to come barging through the door and see me in my half naked squatting glory (I'm a hover-er in public places... especially the gym, they're bad at cleaning). The anxiety of using the bathrooms at this place is enough to give one's heart a cardio workout without boarding a treadmill or bouncing along on an elliptical.
What happened to good old fashioned knocking?! This is how I approach the bathrooms:
1) Soft knock
2) If no answer, try the handle; if answer, move on.
It's really one of the simplest two step processes EVER. SERIOUSLY PEOPLE.