When champion fighter Ronda Rousey recently showed up to the weigh-in for her anticipated UFC fight—slated for December 30 against fellow bantamweight Amanda Nunes—she stared down her opponent with clenched fists and scalp-skimming braids. Mixed martial arts can carry a certain drama, but the tension rang especially true that day: There’s a title on the line, and Rousey is determined to reclaim it.

Meanwhile, the powerhouse athlete and actress has another title to celebrate: Rousey is the newest face of Pantene, with a campaign dropping later today. Calling from the trailer on set, her blonde hair in the able hands of Abraham Esparza (“Abe the braid genius,” she calls him), she paints the scene for Vogue.com: “It’s the part where we break into a top-secret building, they suspend me from the ceiling, and we get this shot of my braid,” Rousey explains, adding a beat later, “I’m just kidding!” For someone who has amassed an arsenal of hard-hitting punches, she is refreshingly disarming: joking about the civil wars over conditioner that broke out among her sisters, nerding out over the cartoon heroine She-Ra, reflecting candidly about the body’s seasonal swings. “I like that my life is cyclical—that I’ll get in super-good, ripped shape sometimes, and then I’ll have my time off, and it’s, like, curvaceous time,” she explains. “I appreciate both of them.”

And so do her legions of fans, who have lined up to see Rousey on-screen (Entourage, Furious 7) and in the MMA octagon, as the fight cage is known. When toggling between the two realms, does she find herself more comfortable in one than the other? “ ‘Octagon’ and ‘comfort’ don’t really go in the same sentence very often, so this is much more comfortable!” Rousey says of the white-glove treatment on the Pantene set. She might be “much more in [her] element in the ring,” she explains, but she’s already a close-knit part of the hair-care brand’s family. “When I came to the fitting, the first thing they said was, ‘You smell like Pantene.’ And I thought, ‘Excellent!’ ” she recalls with a laugh. Here, the Olympic bronze medalist in judo talks about the enduring power of female role models, her go-to power breakfast, and the prefight hair routine that gets her in the zone.

What was your reaction when you heard the news about the Pantene contract?

I called all my sisters because we used to literally go to war over conditioner, and I was like, “Conditioner forever for everyone!” Then I was just super-stoked: “Wow, I’ve got Pantene-level hair!” I felt very proud.