Deadspin has an amusing history of the sports bra, along with patent analyses that explain how sports bras keep you comfortable and unbouncy and whatnot.
Many fun tidbits in the history of this piece of sportswear! For example, the first commercially available bra designed for sports was called the “Free Swing Tennis Bra” and was produced by the fantastically named Glamorise Foundations in 1975. The first actual sports bra was developed by Lisa Lindahl, a jogger who made a list in 1977 of all the things required in a "jockstrap for women," including no "poky hardware" (thanks, lady).
Facts like these keep your dinner party conversation fascinating.