A new fabric becomes more breathable as you work up a sweat
Fibers in the textile collapse or expand based on skin moisture
![breathable fabric](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2019/02/020719_mt_fabric_feat.jpg?fit=860%2C460&ssl=1)
ADAPTABLE FABRIC Material knitted from special humidity-responsive yarn becomes more insulating or breathable, depending on how much you’re sweating.
Faye Levine/Univ. of Maryland