And yet, and yet...more and more people are seeking to challenge themselves in this way. Obstacle racing is becoming a new badge of honour on either side of the Atlantic, and the people behind Spartan Race appear to have got the sadistic/masochistic mix in a particularly well-judged balance judging by the increasing numbers of people they are getting into their events.

The Spartan Race involves cargo netting...

When Spartan Race staged an exhibition showcase recently in Times Square, New York, there was worldwide coverage, including a feature on the David Letterman Show.

Spartan, who now claim to be the world's leading extreme adventure/obstacle course race organisers, plan 78 events worldwide a year, across the Americas, Europe and Australia, an increase of nearly half on the number staged last year. In 2013, Spartan races are also planned in India, Slovakia, Mexico, Canada, the Czech Republic and, soon, China.

At Spartan Race's first event in Britain in 2010, held at the British Army training facility at Bassingbourn Barracks, Cambridgeshire, 1,000 took part. Last year, 25,000 UK racers chose to put themselves through courses inspired by the military discipline of the peerless Spartan warriors of ancient Greece. In 2013, seven races at venues including London, Edinburgh and Cambridge will draw an estimated record 40,000 UK entrants.

Obstacles are kept top secret on purpose to surprise racers, but they may tackle 15-foot rope climbs, slippery 7-foot ramp scaling, spear target-throwing, carrying sandbags up steep hills and barbed-wire mud crawls.

Would-be Spartans may also have to scale 25-foot-high cargo nets, leap through fire, clamber semi-submerged through dank, claustrophobic drainage tunnels, and endure sub-zero ice-pit plunges.

Time penalties are common, punishable by a compulsory set of 30 burpees, meted out irrespective of gender. Before the finish, a phalanx of muscle-bound Gladiators armed with pugil sticks – think of giant cotton buds – attempt to sweep competitors' feet away.

"We've seen a huge increase in participation," explains Richard Lee, the 6ft 2in former Royal Marine Commando who is now Spartan Race's UK Race Director.

...and it involves mud, then climbing up ropes...

"It is not something we could ever have predicted. Worldwide, we've gone from 5,000 people in four races in 2010 to 20 races with 250,000 participants in Year Two, 750,000 participants in Year Three, and we are going to end our fourth year with 1.5 million participants worldwide."

I am trying to concentrate on the figures, but it is proving a little difficult given the presence of a female Spartan in ancient Greek garb. Had this particular version of obstacle racing been called Athenian Race, Selica Sevigny – Lee's fiancée, who is also a Spartan champion and race director – would be in heavy clothing. Indeed, she might not even have ventured out of the house the pair share in Ely, near Cambridge.

But Spartan women, as Sevigny can vouch, were allowed unparalleled independence and freedom within ancient Greece, and were allowed to play with the boys in skirts slit up the side to enable freer movement. Which explains the theatrical garb she sports right now.

Lee and Sevigny fell in love in the biscuit aisle at their local Sainsbury's. No they didn't, of course they didn't, they fell in love while walking the 2,200 miles Appalachian Trail up the east side of the United States and then confirmed their fondness for each other by taking part in the Death Race held annually in Vermont which involves 48 hours of physical exertion and mental humiliation, so far as one can gather. Lee, at his first attempt, came joint first.

Together, they are a hell of a combo. Both are patently excited by the growing success of Spartan Race, which signed a five-year deal with Reebok in January. As they set out their plans, they regularly swap the narrative between themselves, finishing or starting each other's sentences.

Lee, 30, spent years undergoing gruelling exercises at the Commando Training Centre for the Royal Marines at Lympstone, between Exeter and Exmouth in Devon. He knows all about horrible scenery, and waxes lyrical about some of the delights in store for those taking part in the British racing circuit which has been set up.

Sparta was the dominant military power in ancient Greece where the social system was based on military training and excellence, and Spartan Race attempts to draw on that fearsome discipline.

Races come in three different sizes – Spartan Sprints (3 miles, 20 obstacles), Super Spartans (8 miles, 35 obstacles) and Spartan Beasts (12 miles, 45 obstacles). On August 25, there will be the opportunity to take part in the first of these for 2013, a Spartan Sprint at Pippingford Park in East Sussex.

"Pippingford Park is horrible," he says. "The mud there is out of this world. There are endless amounts of stagnant pools of water and bogs, very steep hills, and thick, dense, thorny undergrowth – it's perfect, and positively Jurassic. The terrain is savagely tough. We use the same area as the military. The race crosses between two valleys and we deliberately zigzag the course, snaking up and down the steepest hills."

and it involves a lot of effort...

He adds: "Spartan races are physical and tough. Our mission is to get people off their couches and back into the outdoors.

"There is so much variation with this event. We will never give you a course guide. It is very unpredictable, all of the obstacles are a big secret. The benefit of that is you can train all you like, but ultimately we want to throw you a few curved balls."

Sevigny says: "If the race inspires people to just get out of their comfort zone for a day, or if it inspires lasting change, then we've done our job."

Advertising for obstacle races is overwhelmingly macho in tone. The Spartan Race itself words it thus: "Take on the ultimate obstacle racing challenge – Spartan Race. If you have tried trail races and mud runs, and are now hankering for a tough new challenge, then it's time to step up to a brutal Spartan Race...When you want to succeed as bad as you want to breathe, then you'll be successful..."

Others work on the same lines: "Tough enough to take on the monster?" "Are you nuts enough?" "Brutal 10 – tough running." "Dig Deep." "Warrior run."

But Sevigny points out that 45-50 per cent of racers are female. Strange but true.

"If you look at the research on Spartan culture you see that there was great equality between men and women," she says. "Men did consider women as equals. We get a number of pregnant women competing, and women who are wanting to recover their fitness after giving birth.

"Women compete together in groups too – after giving birth they will start walking, doing yoga and then many of them enter Spartan race."

...and potential singeing...

Lee takes up the running: "We have had teams of up to 300 females who have all trained at the same boot camp – they will get all their friends involved. We get hen dos, family reunions, dates, proposals. Even weddings. At one event in the US a couple planned to get married on the race and had the minister running with them. And they invited the wedding party to the race.

"We want to get everyone you can think of involved. We can see people's perceptions about the race changing and growing. If you went up to someone in the general public and said 'Hi, do you want to run a marathon?' the perception is that there is this huge, unattainable goal. It's incredibly satisfying if you do cross the line, but the perception of being unattainable there. People think that a marathon is that it is not something you can do without a lot of work and training.

"It's a similar thing with triathlon. You need to have an expensive bike, you need to be a good swimmer. With our race all you need is a pair of trainers."

While loving care is taken to select horrible places to compete, Spartan Race has experience of staging itself in big stadiums, and has plans to bring that to Britain.

...and some icing...

"Our first stadium series race was last November in Boston – at Fenway Park, the Boston Red Sox stadium," says Lee. "We sold out Fenway Park at the weekend in a Saturday-Sunday event. We put all of the obstacles in and around the stadium – so we had people going up and down the steps, and then zig-zagging all around the stadium – we had ropes suspended in the rafters. We turned it into a giant obstacle course, and people loved it.

"We held another race in City Field, the other big stadium in Boston, last week. That went well too, and we have a lot more stadium races on the schedule.

"Twelve months ago people hadn't heard about us, but now they are starting to hear about it. It's become a bit more mainstream, we've got a bit more credibility, and now that Reebok have come on board for next five years they are really pushing it.

"We can now say to people, 'Look, we are not just this crazy obstacle race, we can tailor it and make it bespoke to a stadium.' The best part about Spartan is that it is so location specific. Every location has its own personality. We might have one that's in a quarry, we might have one that's in a dense, wooded forest we might have one that's in a ski resort. It means that you can really play with the terrain and use the particular features for events."

Plans for next year will centre upon a world championships which will be held in – Sparta.

"We are going to try and get all our top athletes to Sparta, and we've got a grand prize of half a million dollars," says Lee.

"We have a range of competitors involved. We have Olympic cross country skiers, we've got biathletes, we've got Olympic athletes, we've got a whole spread of really top level athletes competing in the Spartan races.

"But the interesting thing about participants is that if you are at a good fitness level you can compete up there with these Olympians and elite marathon runners.

"For instance, when we held an event last year in Ottawa, we had this guy, who on paper, had 11 titles. So on paper it was a no-brainer. But we had it on a ski resort, and you had to do six ascents of the height of Ben Nevis, so it was an intense race, and by the time of the last climb he hit the wall, he was so physically exhausted that he got passed by a 17-year-old fitness instructor. This guy has competed in two Olympics, and along comes this 17-year-old who is a personal trainer in a local gym who ends up beating him."

Sevigny says the idea of the Spartan Race is to create as much of a mental as a physical challenge. "The thing with the Spartan Race is we create obstacles which are a metaphor for life," she says. "Typically, the Wall. Right before the finish line we have a giant..." Lee takes it up: "45 degrees slope..." And she resumes: "Right, by that time you are so exhausted, you are looking at it, and most people doubt, they think 'I can't do this' and somehow they do. They find a way of doing it. They work together. Sometimes people attempt it eight, ten times, but they do it."

...and, it is to be hoped, a happy ending.

Lee adds: "Having that at the finish line you have thousands of people watching you cheering you on. At a race recently we had a girl who had been trying for 30 minutes and she finally made it. The crowd just goes crazy."

And now Sevigny takes up the running: "We have had emails from people saying 'this race has opened up my confidence, this race has helped me write my first book, we've even amputees who have done this race, he was there with his comrades and they were doing it together. We have competitors from four to 73. It's really a race where you can take part no matter old how old you are or what your rate is. You are not alone and you can get through this."

Lee says organisers are increasingly won over by their flexibility. "People like the fact that it is a mass participation event, and the fact that we are accessible. And also the fact that we have done it before in a stadium. Because a lot of the races we put on are in almost primeval conditions. But we can scale everything to a stadium.

"Our goal is by 2015 to have 150 races in America. We are also in France, Germany, the Czech Republic, Slovakia, Australia and Mexico. And we want to do the same thing in Britain, to have a race on in all the big cities like Leeds, London, Manchester. We want them all to have some kind of Spartan Race, to develop the sport of obstacle course racing."

Ruthless ambition of which the Spartans would no doubt have approved.

Mike Rowbottom, one of Britain's most talented sportswriters, covered the London 2012 Olympics and Paralympics as chief feature writer for insidethegames, having covered the previous five summer Games, and four winter Games, for The Independent. He has worked for the Daily Mail, The Times, The Observer, The Sunday Correspondent and The Guardian. To follow him on Twitter click here.