What is the average capacity of the human bladder? Can one increase their bladder capacity?
Here ya go (quote below). Doubtless this varies between individuals but this should do as an average. I would assume your bladder size is your bladder size and not much can be done to increase its capacity but I don’t really know. More likely I think would be training yourself to go a bit longer before the urge to urinate strikes you. I’ve know some people who have to urinate frequently while I seem able to go much longer despite us both drinking the same amount of liquids (I’ve noticed this most on road trips when they keep telling me to pull over and I do not have to go at all). Whether this is due to some physiological difference that their bodies produce more urine than mine does or just a better ability on my part to “hold it” longer I couldn’t say.
So, given what you quoted above and my own ability to, “hold it”, as you say, my own theory is that this has to do with muscle control of the urethra.
I have no evidence for this, just common sense and years with my johnson being ok when I could’ve ‘gone’. And this quote from post #2 above.