People often think of roller derby as only a group of "bad girls" on skates shoving, punching and playing rough.

But on Saturday, members of Black-n-Bluegrass Rollergirls sought to educate the public on the sport and raise money for those affected by Spinal Muscular Atrophy.

The group of 20 to 30 women in the Northern Kentucky-based flat-track roller derby league held a benefit skate party at their home base, the Independence Skateway.

The rollergirls will continue to raise money through their Web site (www.black-n-bluegrass.com) and at a 10 p.m. concert Friday at Southgate House in Newport where they will sell Black-n-Bluegrass merchandise.

Among the two events and Web site donations, the group hopes to raise $1,500 for their cause. They raised $521 Saturday.

An insurance agent by day and a rollergirl at night under the name "Loose Lee," Amy Moloney first became involved in the cause at a charity drive at work and now knows many of the children in the area suffering from the disease.

The Rollergirls will also try to destroy some myths about the sport in the process, said Amy Hamlet, 32, a.k.a Morgue Ann Le Slayer.

"It lets people know what we are all about," said Hamlet, who lives in Independence. "We are here for our community."

Many misconceptions abound about roller derby, a sport popularized in the 1970s and now making a comeback, Hamlet said.

"From the new girls coming into it, I hear that they think it is just a lot of fighting, bad girls, a lot of terms have been coined like 'Sex on Wheels,' " Hamlet said. "There is a lot of training involved. It is a structured sport."

Women of all sizes and ages participate and rules on what types of hits are allowed help keep the sport safe.

But it can still be rough.

"Physically, it is difficult to get used to," Moloney said. "It is a sisterhood. We beat each other up, but it is not a big deal."

For many, the aggression is part of the attraction. That was the draw for Michele Rowe, 36, of Milford, who stands 6 feet without her skates and is also known as Hellin Hazard.

"I'm not a small person," Rowe said. "I'm a big girl and need a way to get out my frustration. It is also a great way to get exercise."

Black-n-Bluegrass Rollergirls has been around for a year and is believed to be the first of its kind in Northern Kentucky.

In their first year, the Rollergirls have practice twice a week and work at raising their numbers to about 30.

By summer, they hope to have matches against other local teams and even travel across the nation.