A) a hotel or other gym with a limited selection might require you to gymprovise in one way or another.
B) you might be such a workout freak that you need to gymprovise to hit that muscle "just right".
You should be careful with option B because it can come across as douchy.
Bill: Man that muscle head is ripped.
Jane: Yeah, he must use gymprovisation to get a body like that.
To Pimprovise is to ball, stunt, or pick up chicks without using lines like "That's just how I do." or "Did it hurt when you fell from heaven?" or any other cliched method.
"Hey man, everytime I use one of my pick up lines, the girl throws a drink in my face, how do you do it?"