Listen to the story here.Roller derby has existed for over seven decades, but in the last several years the sport's leagues, popularity and personalities have grown.Louisville's Derby City Roller Girls have played to packed crowds since 2006 and the game is often misconstrued as an act rather than a sport. Roller derby does has the feel of an old WWF wrestling match; the announcers are bold and loud and the players skate to background music, some with painted faces and fishnet tights, being cheered on by long-time followers and first-time fans.But comparing roller derby to a televised wrestling match is a big mistake, said Melissa Allgeier, player name Mel O"Drama, "jammer" for DCRG.“I think a lot of people still have the vision of the old roller derby on the track where they were throwing elbows and punching people and we don’t do any of that. It’s a sport with rules. If you did any of that stuff they did back then you would be ejected from the game," she said.Roller derby has taken several forms since the 1930s. Both women and men knocked each other around like pro wrestlers, and in some cases the teams even knew the outcome of matches before they started, said Mel O" Drama.But the rules have remained pretty consistent. The point of Roller Derby is to get your team’s lead player—called a “jammer”—to lap members of the other team to collect points. And while parts of roller derby's history haven’t gone away, like the aggressive image, the sport itself has evolved."Strategy’s a huge thing. When we first joined it was go out and hit...go out and kill the jammer. It was the only thing," said DCRG "blocker" Teresa Wallace, player name Lil Bo Teeps. Now, the team spends hours a week practicing and even reviews tape, she said.“We have set up for our league now, its Roller City Derby Girls training. Its a private YouTube viewing where we upload our practices, we upload our games and we require girls to go on and watch and see what’s going on," said Lil Bo Teeps.DCRG isn't the only team bringing up the intensity level in their league. The team they played in March, the Burning River Roller Girls, uses social media too. BRRG blocker Coco Sparks said she Facebook stalks players from other teams.“Especially if there’s a game coming up, I take a look at their profile, maybe take a look at their history and try to get a handle on how they’re feeling. It’s not totally accurate obviously, because nobody’s going to go on there and be like, I feel like garbage today," she said.DCRG has been established as a league in 2005 and was officially established as part of the Women’s Fast Track Derby Association in 2009, which represents nearly 150 teams worldwide.The association is still changing and continues to grow its membership every year. DCRG jammer Kadie McBride, or Lil Rage of Sunshine, said the teams pay to play and they’re each responsible for setting their own schedules.“We’re a do-it-yourself league. All our women skaters also run our committees, and our boards. We have promotion, we have a bout committee, we have merchandise, training, all that stuff that goes into making the outer parts of the league aside from skating," she said.At this point there's not much structure to conform to. Teams generally lead their season into the regional competition, which happens in the fall.This week, DCRG starts its bi-annual boot camp. Of the 15 girls that will come out, it’s likely only a few will make it through.“If they can master those skills in rookie camps, the falling, the hitting, the skating, obviously, all those things we’re going to put them through for eight weeks then they’ll go on to scrimmage camp," said Lil Rage of Sunshine.Louisville’s only team is ranked near the bottom of their region, 21 of 27. That’s partly because they’re just now establishing consistent players and beginning to expand like teams in larger cities. Their opponents, BRRG, draw from the Cleveland's four smaller roller derby teams to make up their traveling team.Before the game, the team meets in the quietest room in the roller rink (pictured). The girls sit geared up, watching a Nike commercial for inspiration and listening to Lil Bo Teeps’ pep talk.“This is our time to do it. It’s okay that they’re ranked higher than us, it’s okay. We want this more, we’ve been working hard," she said.But the women from Cleveland are too quick and strong and the word strategy seems to fall apart during the game, but several fans don’t seem to mind. On the sideline a former player turned referee Vintage Viv (Vivian Thomas), who said she "turned to the dark side" just to have a chance to stay connected to the game, she looks on in admiration.“I wish they would have started back when I was in my 30s but unfortunately they didn’t. It’s going to be interesting to see what it’s like when I’m 60 or 70 years old, because I have a feeling it’s going to be around for a long time," she said.