Have You Cleaned Out Your Teenager's Gym Bag Lately?

As a mom of two active, athletic teens... my, has that wardrobe-in-the-gym-bag changed in the last 10 years! The clothes I find crammed in their backpacks today are all performance clothes. Some silkier, some stretchier, some mesh. Even less stinky in some cases. All faster drying, easier care. So how did that change happen? How did this performance craze evolve?