Ahead of the London Marathon we pick 5 of the world's toughest races
A marathon ain't what it used to be.
Well, the distance is pretty much the same - 26.2 miles. But now people have set their sights a bit higher than a jog around London.
We live in crazy times. Crazy times where people want to run much further.
Marathon de Sables
Location: Sahara Desert, Morocco
Distance: 156 miles
Race: We don't speak French, but we presume it translates as Marathon of the Clinically Insane. Because you'd have to be to run six marathons in six days through the hot, barren Sahara Desert.
It's widely knows as the 'toughest race on earth'. Probably because it's 156 miles long and happens to be in a desert.
We've all run on sand on holiday on the Costa del Sol. Well imagine doing that for six days straight through shoe-meltingly hot sand dunes.
Oh, did we mention you have to carry all your tent, food, water and supplies with you?
Any race where the entry fee covers the cost of repatriating your broken body gets alarm bells ringing for us.
Location: Canadian Arctic
Distance: 120 or 350 miles
Race: If you're not a fan of slogging your guts out through sun and sand, then this could be the race for you.
The 6633 Ultra takes place in the Arctic Circle, so it's colder than an Eskimo's sh*thouse.
They call it the 'Toughest, Coldest and Windiest Extreme Ultra Marathon on the Planet.' And if that's your bag, the race sees competitors running/jogging/walking/crawling with sleds across snow and ice for 120 miles (though there's a 350-mile extended version if you're game).
Mercifully there are check points every 23 to 70 miles with hot water and shelter away from the sub-zero temperatures.
Make sure you take a jacket and pack some Bovril.
Distance: 188 miles
Race: Probably named as such because you'll be dragon your sorry arse across the finish line by the end.
This is a seriously tough race for seriously tough runners across some of the toughest terrain Wales can muster. (You get the picture - it's tough).
So pant-sh*ttingly tough in fact, that after its debut in 1992 it wasn't held again for 20 years.
Now the beast is back and it follows the mountainous spine of Wales from Conwy Castle to Carreg Cennen Castle over five torturous days.
You'll be wishing you signed up for the London Marathon after all.
Distance: 143 miles
Race: Who's the king of the swingers, the jungle VIP? Well, the Jungle Ultra will certainly sort the men out from the boys.
Not only do you have the ultra-marathon distance of 143 miles to content, but everything the Amazon can throw at you on top.
Runners must battle through rivers, mountainous roads, forests, dirt tracks and snakes while descending 10,500ft down into the Amazon Jungle.
You might want to take a drink because the humidity levels can reach 100% - so don't even bother sweating because it won't cool you down.
Again runners have to carry their own water supply, tents, food, hammock and presumably next-of-kin details.
Try tackling that dressed as a giant bunny.
Distance: 153 miles
Greece's economy is on its arse, and so will you be after tackling this humdinger of an ultra-marathon.
This is taking running silly distances back to the old school, where running silly distances first began.
Greece invented the marathon - so this gives the race added prestige.
Basically it's a race which follows in the footsteps of ancient Athenian messenger Pheidippides who ran the distance to ask for help before the Battle of Marathon.
Two things - the chap dropped down dead after doing the 26.2 mile run, and this race is 153 miles.
We're not great at maths but it sounds a little on the dangerous side.
Still not hardcore enough for you?
You could really show off, and just run around the whole world like this guy.
No-one wanted to race him for some reason.