RONDA ROUSEY, THE TOUGHEST (AND SEXIEST) MMA-ER IN THE WORLD

By Mary Cunningham

If boxing is the Sweet Science, as described by famous journalist A. J. Leibling, how does one describe mixed martial arts?

The Bittersweet Science?

The Science That Defies Description?

The Hammer and Tong Science?

For instance, why did Ronda Rousey get into the game?

“I was bartending and I needed tips,” she says with a laugh.

She may be the best mixed martial arts fighter in the world, and as she is putting her 10-0 record on the line Saturday in UFC 184 against Cat Zingano — the biggest year of her professional life — Rousey feels like she’s come to terms with herself as a fighter, as an entertainer and as a woman. More importantly, she knows how to balance the wide-ranging responsibilities and expectations that accompany these roles.

Rousey refuses to shrink from either identity. As a stylist spritzes hairspray and a makeup artist dabs a brush across Rousey’s face, it’s easy to forget she can snap an opponent’s arm, and watching her pummel another UFC opponent doesn’t call to mind fashion shoots.

That’s exactly how Rousey wants it. She wasn’t always comfortable with the baggage that came with these truths — not girly enough for teenage cliques, too pretty to be taken seriously as a fighter — but today she finds zero shame in either. It’s her modern-day take on what exactly femininity entails: the beauty and the beast.

“I don’t think you have to forego or shame women for embracing their sexuality,” she said, “or their professions or anything like that.”

Rousey’s appearance has helped propel her fighting career, and her fighting career has created a marketplace for her looks. UFC President Dana White calls her a pioneer, someone he thinks is at the front of a “female revolution” both in the sports world and beyond.

“She’s changing the way we look at women,” White said. “And she’s changing the way women look at themselves, definitely little girls. When we were growing up, you were told, ‘You little girls play over here and boys play over here.’ Ronda Rousey smashes that whole thing.”

Truth be told, fighting was always the easy part. She was, after all, a two-time Olympic judoka. The rest has taken some adjustment, though. Family photo albums are filled with awkward, crooked smiles and baggy clothes that hid Rousey’s body. She didn’t wear makeup until she was 21.

As her mother points out, Rousey loves getting “dolled up” whenever she leaves the house these days — and with good reason. She’s a certified Hollywood vehicle. She appears in two movies coming out this year — “Furious 7” and “Entourage” — plus there’s a book in the works, a Reebok contract and regular appearances in glossy magazines, in which she bares everything except, to use her words, her “cash and prizes.”

White famously vowed to keep women out of the UFC and now concedes that no men are as technically sound as Rousey when it comes to a judo throw or an armbar. Few others have created as much separation from their peers. White joked recently, “She’s gonna have to start fighting men if she walks through Cat Zingano.”

“The thing that’s scary is, Ronda’s still learning,” White said. “Every time Ronda comes out, she looks better. She came in here as a judo fighter. Well, now she’s becoming a well-rounded fighter.”

With some of UFC’s other top headliners embattled — Jon Jones and Anderson Silva both recently failed drug tests — Rousey appears to be the sport’s most stable mega-star. Suddenly, UFC might need Rousey more than she needs it.

Rousey is the latest champion with crossover appeal. In many ways, her celebrity is bigger than UFC. She’s retained agent Brad Slater from William Morris, who also works with wrestler-cum-actor Dwayne “The Rock” Johnson, and fields more pitches than she has time.

“I always prioritize fighting first,” Rousey said. “Everything comes from fighting. The only reason Hollywood is interested in me at all is because I fight and I win. So I have to protect that.”

While she could walk away from MMA today and carve out a formidable non-fighting living — not unlike Gina Carano, the former fighter who appeared in “Fast and Furious 6” — Rousey said that’s not under consideration. The money, she said, is a perk; the actual fighting is something more primal and innate. “It’s just what I was born to do,” she said.

Nonetheless, it’s a juggling act. Her coach, Edmond Tarverdyan, said that once training camp begins, no one around the Glendale Fighting Club talks about scripts or Hollywood. Celebrities don’t stop by the gym, and Rousey doesn’t take on any other work until after a fight.

“We always keep it very strict,” Tarverdyan said.

That’s the only way. Rousey filmed “The Expendables 3” in the months leading up to her December 2013 bout against Miesha Tate. Several weeks on set in Bulgaria kept Rousey on edge, and Tarverdyan said his fighter “got a little sick.”

“When she came to camp, we had 45 days to prepare,” Tarverdyan said. “I was a bit worried, I’ll be honest. . . . She wasn’t in the shape I would want to see her in when she starts camp. We did the best we can.”

The result: Rousey beat Tate at UFC 168, deploying an armbar in the third round. It was Rousey’s only pro fight that lasted past the first round.

“I don’t want to make excuses, but Miesha is a lucky girl,” Tarverdyan said.

Fight fans know her backstory by now. Rousey was born with her umbilical cord wrapped around her neck. She didn’t speak in sentences until she was 6. Her father committed suicide when Rousey was 8, after breaking his back in a sledding accident and becoming sick. And when Rousey was 12, still grappling with grief, she began studying judo at the urging of her mother, AnnMaria De Mars, who had been a world champion judoka herself when she was younger.

“I really do believe judo saved me from following a much darker path,” Rousey said.