If so, what’s the problem with having a “shvitzy” pair and washing it like we do to our T shirts and sports clothing?
I’m not saying those rabanim are right or wrong, but the difference from using the bathroom and playing sports is obvious. Having the use the bathroom is involuntary, but playing sports is voluntary. Obviously you don’t hold that this difference is relevant, and perhaps you are correct, but the point is that there are those who would make the chiluk.
Should it become extremely hot, there is always the option to put them in my backpack.
Doesn’t that contradict what you said earlier: However, every serious frum rov will simply tell you if you ask him, that in that case, you simply shouldn’t do that sport/activity. Obvious solution.