It can also be like a high-stakes game of tag, similar to the opening scenes of James Bond flick, "Casino Royale."
"Parkour is what you might do if you're trying to get somewhere as quick as possible or run away from something as quick as possible," said 25-year-old Brian Belida, a parkour aficionado from Frederick, Md. "It's all about efficient movement, very fast movement - getting from here to where you're going as quick as you can."
Hall and Belida are part of a broader effort to build up a community of parkour enthusiasts in Frederick and Hagerstown. Hall and several other traceurs - the name practitioners of parkour use to refer to themselves - meet up Saturday mornings in Frederick's Baker Park, using the park as one huge training ground.
Hall said it took him a while to pick up the vocabulary and proper technique of parkour. Until he met other traceurs in the region, he relied on online communities like Americanparkour.com.
"I train alone most of the time because there's not as many people training out here as there are near D.C. or Baltimore," Hall said.
Mike Spinnler, director of the JFK 50-Mile ultramarathon, said parkour and free running aren't mainstays in the competitive running world.
But Belida said it's gaining traction in the fitness world, as more and more gyms and personal trainers tout alternative exercise formats.
Spinnler, a distance runner and a former steeplechase competitor, said the key differences between parkour and free running are that for steeplechase, there are standardized "barriers" the runner must clear. Though cross country courses can vary depending on the terrain, there are still standardized distances and a set finisher and winner.
Spinnler attributes recent interest in free running and parkour as an extension whatever was driving the interest in extreme sports. He said this has manifested itself in a recent increase in ultramarathon entries. This year, registration opened to the public on July 8, but by July 11 it had reached its 1,000-runner maximum, Spinnler said.
"Up until three years ago, we were able to take race entries up to race day," Spinnler said.
But parkour isn't a race for a prize.
"I look at it as a discipline," Belida said.
Hall said parkour was developed in France by a man named David Belle, and was based on his father's firefighting training. Its practice is generally urban-based, where traceurs and traceuses - women practitioners - use city terrain as a giant training ground.
Often, groups use parks and playground equipment to safely practice vaulting.
At Baker Park in Frederick, Belida didn't wear gloves during parkour because he said liked to feel his environment. He has the calluses to prove it - they caked up at the base of his fingers like rivets of dried skin.
"It actually helps to build up calluses," Belida said. "The first time I started doing parkour I tore up my hands pretty bad."
Hall arrived at Baker Park barefoot. He later explained that this has more to do with some of the roots of parkour - to pursue a natural method of training and have your body close to how it would be in nature.
"To be as close to where our bodies would be, you would train barefoot and with as little clothing on as acceptably possible," said Hall. "So, no shoes."
Hall is studying kinesiology and hopes to transfer to a four-year school, perhaps in Utah. He says his initial interest in parkour came from wanting to be a Marine. Hall said he's not pursuing military life today, but his interest in parkour has expanded into a broader philosophy: an alternative approach to overcoming life's obstacles.
"It teaches you responsibility over other people and helps you know confidence in your entire life of saying I can overcome that obstacle," Hall said. "If somebody needs help, I can help them. You don't feel you have to defer to a higher authority. You're self-reliant. You can take care of yourself and take care of other people."