more than 10,000 adrenaline junkies took on 'america's toughest obstacle course' in california on sunday with a photographer on hand to document their pain stricken faces lucy nicholson of reuters snapped away at various points on the 12 mile tough mudder course in san bernardino as contestants courageously made their way through mud pits, iceberg baths and fields of live wires in almost 90 degree heat one shot shows a man in seeming agony as he's shocked by electric wires while another shows a contestant welling up as he crawls through a haze of tear gas later in the course, a couple were photographed sharing a passionate embrace after navigating a tunnel of barbed wire both of their  t shirts appear coated with dirt scroll down for video  hair raising: more than 10,000 adrenaline junkies took on 'america's toughest obstacle course' in california on sunday with a photographer on hand to document their pain stricken faces   here a man screams as he is shocked by electric wires  plop: spectators watch on as tough mudder participants wriggle through pipes and plunge into a pool below  crossing the line: lucy nicholson of reuters snapped away at various points on the 12 mile tough mudder course in san bernardino as contestants courageously made their way through mud pits, iceberg baths and fields of live wires in almost 90 degree heat  caught on camera: one shot shows a man in seeming agony as he's shocked by electric wires  tough mudder, which was started by two harvard business school graduates in 2010, is an endurance event series which now takes place all over the world despite the rather unpleasant obstacles, the events have become so popular that many of them sell out weeks in advance one participant at sunday's tough mudder in california explained why he had signed up for a second year running 'it's about being with your friends, pushing through everyone here is your friend, everyone's your family that's all there is to it anyone can do it,' he told ruptly tv at the end of the course, contestants are rewarded with a tough mudder sweatband and an ice cold beer at most events, tough mudder also offers tattoos of its logo to all finishers who want to commemorate their achievement the event founders highlight that tough mudder is a 'personal challenge' and not a race, therefore no one is timed and no medals are given out however, participants generally finish the booby trapped tracks in around three hours the next tough mudder events are set to take place on may 2 and 3 in london, texas and atlanta the average age of contributors is 29, with 70 per cent male and 30 per cent female new recruits: tough mudder, which was started by two harvard business school graduates in 2010, is an endurance event series which now takes place all over the world  swinging success: despite the rather unpleasant obstacles, the events have become so popular that many of them sell out weeks in advance  crawling low: the obstacles often play on common human fears, such as fire, water, electricity and heights  soaked: a man climbs out of an icy water tank during the tough mudder 10 12 mile obstacle challenge in california on sunday  still afloat: an average 78per cent of tough mudder entrants successfully complete the course  following the leader: the first tough mudder challenge was held in the us in 2010   to date, more than 13 million people worldwide have participated in the events  tearful expression: a man scrambles through tear gas during the tough mudder 10 12 mile obstacle challenge in san bernardino, california  determination: at the end of the course, contestants are rewarded with a tough mudder sweat band and an ice cold beer  a messy affair: most participants end up ditching their clothes around the course as they get coated with mud and sweat  ready for more: the next tough mudder events are set to take place on may 2 and 3 simultaneously in london, texas and atlanta  source of support: a couple share a passionate embrace after navigating a tunnel of barbed wire 
harvard business school london texas atlanta 30 per cent 2010 sunday thousands california tough mudder may 2 70 per cent san bernardino
tough mudder, which was started by two harvard business school graduates in 2010, is an endurance event series  on sunday thousands flocked to  san bernardino in california to take on the challenge  the next tough mudder events are set to take place on may 2 and 3  in london, texas and atlanta  the average age of contributors is 29 with 70 per cent male and 30 per cent female 