The only man on the planet to run seven marathons in less than seven days on the seven continents is aiming to go one better by smashing the five-day barrier.
Irish ultra runner Richard Donovan starts his epic quest in the extremes of Antarctica running the first 26 mile leg in -20C at the Russian Novo science base next Wednesday.
The 45-year-old father-of-one is doing the endurance challenge on a shoestring budget out of his own pocket to raise awareness of the humanitarian crisis in the Horn of Africa. His record stands at five days, 10 hours and eight minutes - 130:08.
"It's been very hard to figure a way of knocking off the half day," he said. "I'm keeping it real - I'm not going in some privileged manner. I'm going against all the rules, no special diet, flying economy by myself, bringing whatever I can fit in one bag. I'll sleep where I can."
Donovan, who was inspired to first attempt the challenge in 2009 after the failed bid by British explorer Sir Ranulph Fiennes, will set the countdown clock ticking from 120 hours. The first run begins on February 1 when pilots of the Russian cargo plane are given a take-off slot.
Donovan, from Galway and an experienced marathon runner at both poles, said sleep deprivation and massive temperature fluctuations will be the biggest challenge. Despite this he has received no specific medical advice and has not seen a doctor in years.
Money raised through online donations at www.worldmarathonchallenge.com will go to Irish aid agency Goal, one of few charities working in the Horn of Africa. Running times will be independently verified at each location.
Donovan has ruled out using energy gels or drinks for fear of sickness and the only supplement he will pack are salt tablets. He will have about nine hours in each location to disembark, run the course and fly out to the next destination. "I'm used to moving on dead legs and not having to think about it but that does not deny the fact that they are dead," he said.
Donovan's round the world marathon timeline starts on February 1 at the Russian Novo base, with temperatures of -20C, before moving on to Cape Town. He will then arrive in Sao Paulo, Brazil on February 2, where he will battle 20C temperatures and high humidity.
The day next he arrives in Orlando, USA, the following day London Gatwick, by which point he will have run 131 miles and flown 26,560km. Marathon number six will take place in Hong Kong, on February 5, where the average temperature is 15-18C, and number seven in Sydney, where he will have a 1900 deadline. By this point he will have run 183 miles and flown 43,540km.