Free-runners Cali (real name Frank Nelle), Majora, (real name Marwan Elgamal) and Asid (real name Yusuf Yirtici) demonstrate free-running in front of the London Eye August 27, 2008. Freerun, is based on the theory of Parkour, which uses the body to get from A to B as quickly and efficiently as possible, but its practitioners place greater emphasis on individual expression, creative flow and artistic merit. Picture taken August 27, 2008. To match feature BRITAIN FREERUN REUTERS/Luke MacGregor (BRITAIN)