Marathon man Richard Donovan broke his own record by completing his final run in Sydney to make a total time of four days, 22 hours and three minutes.
The 45-year-old admitted that sleep deprivation, running, and travelling through different time zones and temperatures had taken its toll on his body.
“I was absolutely wrecked. I wasn’t even able to keep down water,” he said.
“We came to desperate measures in Sydney and I chanced a beer.
“I had one bottle of Heineken during the race for some carbs and one at the end of it.
“It was the first time something stayed down in days.”
Mr Donovan, a father of one, began his epic quest in the extremes of Antarctica last Wednesday, running the first 26-mile leg in -20ºC at the Russian Novo science base.
He has since run 183 miles and flown 27,055 miles.
His round-the-world marathon took him from Antarctica to Cape Town, South Africa, to Sao Paulo, Brazil; Orlando, USA; London; Hong Kong and finally Sydney.
His previous record stood at five days, 10 hours and eight minutes.
Mr Donovan completed the endurance challenge on a shoestring budget out of his own pocket to raise awareness of the humanitarian crisis in the Horn of Africa.
Money raised through online donations at www.worldmarathonchallenge.com will go to Irish aid agency Goal.
Travelling alone and flying economy class, he said the hardest part was concentrating in airports and catching flights while fatigued.
But the Galway man, who is an experienced marathon runner at both poles, commended race organisers and supporters in each city, which included the Brazilian air force, athletics chiefs and former Olympic Games officials.
“I have a lot of training behind me as an ultra marathon runner so I have a certain amount of experience of moving while dead on my feet, and that helped the mental and physical and emotional management,” he said.
“I never contemplated I was not going to finish.”
Mr Donovan is chairman of UltraRunning Ireland. He has won the Antarctic Ice Marathon, the Inca Trail Marathon, the Everest Challenge Marathon, the Antarctic 100km and the Himalayan 100-Mile Stage Race.
Mr Donovan, who was inspired to attempt the challenge in 2009 after the failed bid by British explorer Ranulph Fiennes, revealed he has no desire to set another record.
“I plan to lie down on a beach tomorrow and the day after and leave here on Thursday so I’ll be back in Ireland on Friday,” he said, speaking from his bed in Sydney.
Richard Donovan became the first to run a marathon at both the North and South Poles in 2002.
* Richard Donovan is a world leader in the field of ultra distance running.
* He became the first to run a marathon at both the North and South Poles in 2002 and has run in some of the most unforgiving climates and challenging terrain in the world, including the Sahara Desert, Mt Everest, the Inca Trail, and the Amazon jungle.
* He has won the Himalayan 100-Mile Stage Race, Everest Challenge Marathon, South Pole Marathon, Inca Trail Marathon and Antarctic 100k three times.
* Richard, who is the chairman of UltraRunning Ireland, organises the northernmost and southernmost marathons on earth: The North Pole Marathon and Antarctic Ice Marathon.
* He brought the first international ultra event to Ireland, the Celtic 100k, and was race director at the inaugural Commonwealth 100km Championships in 2009 and the World 50km Trophy Final in 2010.
* He organised the globally broadcast International Association of Ultrarunners Trail World Championships in Connemara held last July and was race director at the Commonwealth Trail Running Championships in Wales in September.
* Last December, Richard set a new record when running 100 miles in -25C in Antarctica in a time of 24:35:02 hrs .