If you see a group of guys scaling down the side of a building, jumping over rails, or somersaulting over paving stones, don't be alarmed - there's is a good chance they are members of the free running group Zippies.
Free running, or parkour in French, is neither a sport nor martial art, but a blend of both with a touch of urban edginess.
Created by Frenchman Sebastien Foucan and David Belle and introduced in Hong Kong about two years ago, free running incorporates death-defying, but beautiful, jumps from rooftop to rooftop, sprints interspersed by leaps over railings, and flips and kicks off walls.
Some argue that free running and parkour are separate disciplines: free running highlights the style and fluidity of movement while parkour enthusiasts aim to reach a destination as quickly as possible.
But fans of both will agree that free running requires a passion for sports and a high tolerance for adrenalin overload.
With these two traits, a pair of protective gloves and shock-absorbent shoes, anyone can learn free running.