It involves running through fire and ice pits, crawling under barbed wire, getting bruised and covered from head to toe in mud.
The assault course in Perton, Staffordshire is run by ‘Mr Mouse’ a former Grenadier Guardsman Billy Wilson.
This weekends race, the 25th, attracted runners from 25 different countries around the world, with many competitors flying in from the US.
This weekend saw competitors haul crucifix’s, plunge themselves into a frozen lake, crawl through thick mud under barbed wire and get electrocuted.
Making the whole experience more difficult are the marshals dressed as commandos fire blank artillery shells and throw thunder flashes and smoke bombs at the competitors as they struggle through the course.
Up to a third of all competitors fail to make it to the finish line every year, 6000 people took part this weekend.