Why is casual clothing referred to as "sportswear"? What has it to do with sports?

Question

I'm not referring to sweats and the like. I mean things like casual pants, sportcoats (there it is again), blazers, golf-shirts, ladies' slacks, blouses, etc. Basically, anything that's not a suit.

Answer 1

sportswear is like sweatpants and stuff. cuz its something that you would wear to the gym.