Participants get underway at last year's Tough Guy competition, held in South Perton, Staffordshire. On average, two-thirds of competitors do not finish the 12km race, which consists of cross-country running and an assault course.Photograph: Espen Rasmussen/Panos PicturesMen carry wooden crosses, which gives them a head start.Photograph: Espen Rasmussen/Panos PicturesParticipants face a wall of mud.Photograph: Espen Rasmussen/Panos PicturesClimbing along ropes in cold and muddy conditions.Photograph: Espen Rasmussen/Panos PicturesOne competitor jumps through a fire - then has to wade through a muddy lake. Photograph: Espen Rasmussen/Panos PicturesPhotograph: Espen Rasmussen/Espen Rasmussen/Panos PicturesAnd yet more mud. Photograph: Espen Rasmussen/Panos PicturesPhotograph: Espen Rasmussen/otherSo near and yet so far – one participant near the finish line helps another who has cramp.Photograph: Espen Rasmussen/Panos PicturesMeanwhile, back in the mud...Photograph: Espen Rasmussen/Panos PicturesDiving under logs in ice-cold water as a marshal no doubt shouts 'encouragement'.Photograph: Espen Rasmussen/Panos Pictures'Is this the finishing line I see before me?' Photograph: Espen Rasmussen/Panos PicturesWaiting for a warm shower after completing the course.Photograph: Espen Rasmussen/Panos Pictures