The Charm City Roller Girls have a message for all those old-time roller derby fans out there: This isn't your grandma's roller derby.

"All that stuff is actually completely gone right now," says Hilary Rosensteel, a roller girl almost since the team was founded in 2005. And by "stuff," she means the elbows, extravagant cheating and over-the-top showmanship that, back in the '60s and '70s, made roller derby the female equivalent of professional wrestling.

These days, she insists, roller derby is more about competition than show. Not, she hastens to add, that derby has turned sedate, or completely respectable.

"People have retained the characters a little bit, and the makeup, the fake names and all that," says Rosensteel, 39, better known to her fans as Rosie the Rioter. "But the scripted part is completely gone, and now even the sillier elements are completely gone. Now, you're going to see the pure sport."

Which means that anyone going to the Du Burns Arena on Saturday night, as Charm City takes on their New England counterparts, the Boston Derby Dames, should be prepared to enjoy the sport of roller derby as much as the show.

"The theatrical piece of it, the staged fighting and everything, was in it a little bit in 2001," when the sport was revived by a group of woman out of Texas under the name Bad Girl Good Woman, says Rosensteel, who grew up in Frederick watching old-style roller derby on Saturday morning TV. "We sort of learned a little bit of dirty play — elbows and things like that, how to camp it up a little bit. But it was still always genuine, never scripted. That's how it's different."

Roller derby matches consist of three 20-minute periods. Two teams of five players compete in each jam, skating in rings that start 20 feet behind one another. For one designated skater in the trailing team, known as the jammer, the goal is to fight her way past the lead team, using body blows, speed skating and maybe a few tricks to score points for each opposing player she passes. Make it to the front, and she can call off the jam, which otherwise lasts two minutes.

In the old days, back when roller derby was attracting crowds of 10,000 to 20,000 in venues like New York's Madison Square Garden, it was pretty much anything goes for jammers fighting their way to the front (as anyone who's ever seen Raquel Welch play roller derby star K.C. Carr in the 1972 film "Kansas City Bomber" can attest). But today, players are penalized or ejected for fouls and unsportsmanlike conduct.

"There used to be a lot more tolerance of dirty play and elbows, the camp and the wrestling, all that stuff," says Rosensteel, a mother of two teenage boys who lives in Remington. "Tripping, pulling people down — now, you would get ejected from the game and go sit in the locker room."

Not that roller derby has turned into anything sweet and demure, she hastens to add. The Charm City Roller Girls and their sisters are a tough bunch, as skilled as they are fierce.

"We have people that have returned from major breaks to their ankles and legs, who have had hardware put in and are coming back after the hardware is removed," says Rostensteel, who counts a broken finger, torn rotator cuffs, chipped teeth and badly sprained ankle among her injuries. "The legal hard hits, the speed and the strategy are evolving. Those are the important pieces to the actual game and spirit of roller derby. I find that enthralling to watch and be a part of."

Rosensteel joined Charm City shortly after moving to Baltimore in 2005. She chuckles at the memory of the early team tryouts, held at Skateland Putty Hill. She knew how to skate, Rosensteel says, but not everyone did.

"There were a whole lot of people without any skills," she says. And even many of those who knew how to skate weren't prepared for the rigors of roller derby.

"It's one thing to skate," Rosensteel says, "but it's another thing to skate inside of lines, with gear on, and to hit each other and to try to move around each other."

Their first bout, she says, was an eye-opener. "I look back at those video clips and photos, and I am stunned that people even came back for the second game. We looked like deer that were just born on those skates."

But five years on, the team has come into its own. Charm City placed fourth in its region last year, just missing out on a trip to the finals. This year's regional competition is set for September and October, with the finals set for November in Chicago.

But first, there's Boston to get by on Saturday. The crowds at Du Burns, Rosensteel says, really get into the matches and seem to like what they see, regardless of what they expected coming in.

"People come to the games with one thought and concept, and they leave thinking it's really cool," she says, "even though they didn't see fake fights."

chris.kaltenbach@baltsun.com

If you go

The Charm City Roller Girls All-Stars take on the Boston Derby Dames' Boston Massacre at 6:30 p.m. Saturday at Du Burns Arena, 1301 S. Ellwood Ave. In the opening bout, the CCRG Speed Regime squad battles the D.C. Rollergirls All-Stars. Tickets are $5-$25. Information: charmcityrollergirls.com