So is OP.

And that “nonsense” makes perfect sense. Exactly like your sphincter keeps you from shitting your pants, there are muscles that hold your urine in.

What do you think “holding it” means? It means you’re tightening the muscle to prevent flow. The more you have to strain to do so, the more fatigued that muscle gets.

At least they stayed on topic and didn’t try to put anyone down.