The Opponent (2000) on Netflix

Patty is a woman involved in an abusive relationship who decides to take boxing lessons to better protect herself when her boyfriend becomes violent. While practicing at a health club, Patty attracts the attention of June and Fred; She's a female boxer and he's a promoter who books fights at local clubs. Both June and Fred thinks Patty might have what it takes to go pro, and they introduce her to Tommy, a trainer who runs a local gym and who helps Patty get into fighting shape. In June, Patty finds a friend who gives her a good reason to get away from her boyfriend, and she begins a slow but steady climb up the ladder of the women's boxing circuit.