According to an article in Women's Running Magazin...

According to an article in Women's Running Magazine, the first athletic bra, created in 1977, was two jock straps sewn together and call the "JockBra." Come in and marvel at the advances in our evolved 2016 collection. http://womensrunning.competitor.com/2016/03/just-for-fun/running-in-the-1970s_56587