As workers put final touches to a massive arena for Sunday’s cage fight on the White House South Lawn, a few miles away, a professional pianist is learning how to choke someone unconscious.Across the same mat, an immunologist-by-day is teaching students how to pin a struggling opponent.They represent the grass-roots of a US martial arts phenomenon that has brought the Ultimate Fighting Championship (UFC) from what was once derided as “human cockfighting” to the cultural mainstream – and now the White House.“The rise of the UFC has been a stunning thing to watch,” said UFC fighter Ryan Hall, owner and head trainer at Fifty/50 Martial Arts Academy, where the men were training.“A UFC event on the White House lawn – tell me that 10 years ago and I’d laugh at you!” he said.UFC fighter and gym owner Ryan Hall says violence is “part of the magic” of the sport. Photo: AFPThe fighters performing in front of President Donald Trump will blend punching, kicking, grappling, choking and joint locks in contests that frequently leave the mats streaked in blood.