A shoulder to the rib cage and the ensuing sound of knee and elbow pads colliding with the ground amid cheers from the crowd can mean only one thing: It’s roller derby time.

The Underground Derby League kicked off its third season Sunday night at Skateland in Olympia, where about 60 of the league’s members split into three teams: Angels, Demons and Killer Tomatoes.

While there’s plenty of pushing and shoving on the rink, the aggression stays there, says Tiffany “Bam Bam Tiffalo” Duggan, who is entering her second year in the league.

“We leave it all on the rink,” she said.

Duggan, a medical assistant by day, served as a blocker for the Angels, trying to keep the other team’s jammer from skating past to gain points. A jammer is a player who attempts to score points by making her way past other players.

For the women in the league, the competition is just a part of the reason they participate. Duggan said she likes seeing women from all walks of life come together and derby.

“I’ve gained some good friends, and it’s changed my life,” she said.

It’s also changed the life of Danielle “Black Magick” Zinck.

Her reason for joining the league last year stemmed from frustration with the men in her life. She was looking for a place to unleash some anger.

“Now,” she said, “I do it because this is my family.”

Her daughter also participates in the junior league. And her derby family has grown from nine during its first season in 2009 to more than 80 women, said head coach and founder Desi Sordahl.