By Andy Brownstone
Meet freerunner Pip Anderson who's in line to become the world champion.
Pip Anderson, or Piptrix as he's known in the sport, is one of the UK's best freerunners.
The teenager's been doing it for three years, he's on his way to earning a living from it, and he's only 17.
And now he's tipped to take the crown of the first ever world champion.
He told Newsbeat: "It all started when I saw a documentary called Jump Britain. I was already sort of doing it.
"I saw things around me and I just wanted to climb and jump on them."
The sport hit the UK five years ago with the C4 documentary Jump London, which was followed up two years later by Jump Britain.
Since then, the number of freerunners in the UK has steadily grown to around 15,000.
Freerunning consists of combining various tricks, jumps and rolls while running.
And more experienced runners will attempt things like leaping from one building to another.
Pip said: "You have to start small with jumping over a wall, much lower level stuff, so you're not creating the risk of injury.
"But over time you then get onto flips and spins and stuff like that."
The sport comes from the French discipline Parkour, but is different.
Pip explained: "Parkour is more a way of getting from A to B. Freerunning is the English version of it which is much more creative and dancy."
First world championships
Pip's fellow contestant Tim prepares to jump off a wall
It's the first time a world championships has been held in the sport.
The Camden Roundhouse in London has been specially converted for the event.
Each of the 20 competitors will get 90 seconds per round to perform their best tricks, with the winner becoming the first ever world champion.
There's already good money in freerunning, mainly through music videos, TV and film.
Pip hopes to become a professional, and has already filmed adverts for a number of major brands.
The sport has appeared in a number of Hollywood blockbusters, the most well known was the chase scene at the beginning of Casino Royale.
There are also two scenes in the new Adam Sandler movie Don't Mess With The Zohan.
Pip added: "A bunch of films have used it so far, and I'd like to be a part of that for the future.
"There is an element of risk involved. I fractured my hand in six places in one go.
"But if you exercise properly and keep yourself fit it's less likely to happen."