Exactly. I wear all-synthetic when I run or hike, because cotton will get damp and heavy and uncomfortable (potentially unsafe when hiking). I throw it in a ham

Exactly. I wear all-synthetic when I run or hike, because cotton will get damp and heavy and uncomfortable (potentially unsafe when hiking). I throw it in a hamper with a lid - separate from my regular one - when I'm done, and I do laundry a couple of times a week. I have shirts and smalls that I've been using nine years without a problem under this regime. One key, I think, is that I use a "color booster" (bleach alternative) specifically to eliminate the poly funk. Doing a load of laundry for a single set of workout clothes is horrible environmentally. Even when our kid was young, it was every other day at most, and I was running more than that at the time.