whats to elaborate? the shulchan aruch is clear that one may walk unclothed in a bathouse because it is the derech to dress that way in that place. some seemed to be applying that logic to excercise. all I was saying is that just because it is the derech to do something, doesnt mean it is proper (maybe it is the wrong derech).
I dont zumba or do yoga. I’m not female and have no idea how they dress at the gym or what the accepted “derech”, mode of dress is at a womens gym whether with frum women only or any other women. I suppose if my wife asked me if something was appropriate or not, I would think about it then.
Personally, I wear shorts and a t-shirt when I excercise, whether on the treadmill, playing raquetball or basketball. I dont think there is anything inherently untznius in my dressing that way, I just dont dress that way to do shopping or go to work. I am guessing that other people who excercise, male or female, dont think so either.