Editor's Note: On April 23, Jacob Zurl completed his Cuba challenge, cycling 1450km in 58 hours and 48 minutes -- nearly two hours slower than his initial estimated time. The article below was first published on April 18, the day before the Austrian began cycling across the Caribbean island.

(CNN) Sleep deprived, the mind begins to play tricks. Exhausted, the body begs for no more. But Jacob Zurl carries on. He must. Records can only be broken when the spirit refuses to bow.

Enduring when the majority would quit is this Austrian's specialty.

The extreme cyclist lives to achieve the unthinkable: cycling across the Himalayas in a record 39 hours, setting world firsts in high altitude.

This month he is to cycle non-stop the length of Cuba, from east to west, on gravel and dirt tracks, in extreme heat, perhaps tropical rain. It will be humid. It could be 1450 kilometers (900 miles) of hell.

No one has attempted this round-the-clock feat. The 28-year-old hopes to complete his mission -- the equivalent of cycling from New York to St Louis in the Midwest -- in 57 hours. Experienced cyclists would normally take two weeks.

He will, he says, nap for a few minutes, weather permitting, and when nature calls he will hop off his bike. But essential functions will be brief. Time moves forward without rest and so must he.

JUST WATCHED Extreme Cuba: 1450km, 57 hours, 1 song Replay More Videos ... MUST WATCH Extreme Cuba: 1450km, 57 hours, 1 song 01:34

For a little over two days, Zurl will mainly be pedaling, relentlessly so, fighting the aches in the body, the manipulative voices in his mind and whatever the elements throw at him.

It is his inquisitiveness, as well as a love for adrenaline, which drives him.

"When I look at the world map, for me, as an ultra cyclist, I see so many interesting projects," he tells CNN Sport.

"Why hasn't someone done this challenge before? Cuba is such an interesting country.

"I want to get in contact with the people, to know the country. I have endurance in cycling and the Cuban people have endurance in life."

Young men wait by the side of the road for the remains of former Cuban President Fidel Castro to pass by on their four-day journey across the country.

The Caribbean's largest island is experiencing an uncertain era following the death of Fidel Castro in November 2016.

Castro, regarded as a revolutionary hero to his supporters and a ruthless autocrat to his enemies, was the man who created a communist state in America's backyard.

But earlier last year, Barack Obama became the first US President to visit the country in 88 years as relations between the Cold War-era adversaries thawed. It is yet unclear what policy US President Donald Trump will pursue, but it is possible he will harden America's stance towards the island.

Cuba, a country 90 miles off the Florida coast, is renowned for its color and spirit, but its vivacity will not shield Zurl from the agony he will undoubtedly experience as he forces his body to cover a daunting distance at rapid pace.

Riding along, and up and down, rickety roads, his body will rattle as if riding on a pneumatic drill. Crouched for hours, his back will eventually feel as tight as old rubber and his muscles will be as hard as week-old bread.

While the lights on his bike will guide him through dark nights, it is music -- and an iron will -- that will drive this son of a bank manager on when he is sucked into a black hole of physical suffering.

Curiously, he will only listen to one song, a familiar beat, lyrics he can easily repeat. Sometimes, he may even sing along. Quietly, of course, for it is long-distance cycling, not singing, which is his forte.

"I haven't decided what song it will be yet in Cuba," he laughs, revealing that his tune of choice during a recent training stint in Spain was Mumford and Sons' "Believe" before adding that he rode up the Himalayas listening to "Free" by Natalia Kills.

"For the long distance projects, the music makes it easier," he says. "Once my support car drove over one of my MP3 players. That was s***."

Zurl is the sort of man who would feel lost riding without music.

He will take three portable music players to Cuba, a precaution against a repeat of the previous disaster.

For many, listening to the same song for hours, for days, seemingly forever on loop, would be as torturous as pedaling from one end of a country to another at 25 kph.

But when life on the saddle feels effortless, Zurl's mind drifts. He will contemplate about his yesterdays and make plans for his tomorrows. "I'm thinking about everything," he admits.

He hears the music, but doesn't listen. The music, he says, goes "under my mind."

It is when the adventure becomes a chore that Zurl refocuses on the beat of his favorite tune which will push him to achieve a feat no man or woman has done before.

"It's always just one song. It's kind of spiritual. When it's getting hard and I want to listen to music and there is no music, it's a problem for me," says Zurl, who has been cycling an average of 20 hours a week in preparation for this ride, focusing on speed rather than endurance.

"The worst thing to happen in this race would be if I lost my MP3 players."

But Zurl has experienced deeper misery than the crushing of his portable music player.

It was while in Cuba, before his first attempt to cycle across the island in 2015, that Zurl contracted dengue fever.

"I felt suddenly not good," is his understated description of the day he was hastily taken to hospital, his temperature rising to 40 degrees.

Zurl says he fears catching dengue fever again during his ride along the country.

In nine days, he lost seven kilos. He says he caught the tropical disease, which is transmitted by mosquitoes, when cycling in heavy rain during a training session on the island.

He is better prepared for this his second attempt, though that does not mean he has forgotten easily about the fright of two years ago.

Asked what he feared the most about the journey ahead, he gravely replies: "Catching dengue again."

"There was a heavy shower and I didn't have the (mosquito) spray and, I think, that was the problem," says Zurl, regret still in his voice.

"I did not think it was going to be so dangerous.

"I took the plane back to Austria and for the next two months sport was forbidden and, after that, I started to cycling again, but in 2016 I fell ill so many times."

It is Zurl's experience with dengue which partly explains why his family will be close behind in a support car this time around.

His parents, Paul and Brigitte, a medical physicist, and girlfriend, Nina Almer, are the ones who will drive behind with food supplies, isotonic drinks, spare wheels and, of course, his MP3 players.

The mum who once told her then-18-year-old son he was "completely stupid" for spending a vast sum on shoes for his new two-wheeled hobby is now fully supportive of his long-distance expeditions.

"First my parents were skeptical," admits Zurl, once a promising sailor of international class before cycling took hold.

"It needed a lot of energy for me to convince them, but in the last two years or so it's easier and they know, for me, it's important.

"If it's not too dangerous they will let me do it. In the past it was difficult because my father loved to sail and I'd sail in regattas.

"That's all changed. Not only do my parents now cycle, but my uncle and aunt do too. Sometimes we cycle together and we have our own jersey. I made it for them with the family name on it."

It is perhaps fitting that Zurl's mum will be on hand to make sure her son eats properly, though he does not need his mother to remind him of the dangers of not consuming the right calories at the right time. Every engine needs fuel.

Eating for endurance, says Zurl, is a skill. "I really have to eat a lot," he says, sighing.

Experience has taught him he will have to eat or drink 500 calories an hour to compensate for the minerals he will lose through sweating.

Even food lovers would balk at the thought of consuming 30,000 calories in two-and-a-half days -- especially when presented with a diet of rice and potatoes, essential for this race against the clock.

Will Zurl find fresh vegetables along Cuba's dirt tracks?

He says he would love to, but is unsure what will be available en route. Protein bars and drinks, he says, will suffice if fresh food cannot be found.

Photos: Ultra cyclist to cross Cuba in 57 hours Austrian ultra cyclist Jacob Zurl is planning to see Cuba like no person has ever seen before ... Hide Caption 1 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours The 28-year-old Austrian, who is pictured on the waterfront of Havana, will attempt to be the first cyclist to ride across Cuba -- a distance of 1,450 kilometers -- non-stop. Hide Caption 2 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours In 2014, Zurl clocked the fastest ever cycle of the Himalayas (pictured above), covering 530 kilometers in 38 hours and 40 minutes. Hide Caption 3 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Zurl crossed the Leh-Manali Highway in northern India without sleeping for nearly two days, despite extreme temperatures. Hide Caption 4 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Zurl endured much of the ride on poor or unsurfaced roads, battling freezing streams, slush and thin air. Despite that, it took him less than two days to finish a course that many experienced cyclists take two weeks to negotiate. Hide Caption 5 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Seen passing a truck during his 2014 ride in the Himalayas, Zurl also claimed the Guinness Book of World Record in 2012 for the most vertical meters cycled in 48 hours with 28,789 meters of climbing in Austria. That record is now held by Craig Cannon of the US. Hide Caption 6 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Zurl will begin his challenge in Punto de Maisi, the south east of Cuba, and finish in Cabo de San Ant. Hide Caption 7 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours To prepare for the extreme challenge of his Cuban ride, Zuma has been acclimatizing in Cuba in recent weeks. Hide Caption 8 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Zurl will have to eat or drink 500 calories an hour during his Cuba ride. Hide Caption 9 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Zurl initially planned to cycle the length of Cuba in 2015 but fell ill in training.

Hide Caption 10 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Zurl poses in front of the newly opened US Embassy in Havana. The recent easing of US sanctions on Cuba has had an impact on the island's ability to host international sporting events. Hide Caption 11 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Four rather than two wheels ... Havana is full of classic cars from the golden age of American automobiles. Hide Caption 12 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Zurl cycled in Iran in December as part of his training for his Cuba challenge Hide Caption 13 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Zurl averaged 13.7 kilometers per hour during his two-day race in the mountains of India. He will likely top that speed in Cuba, which presents a flatter terrain but is not without its own extreme conditions, notably humidity. Hide Caption 14 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours "You have to train a lot of years to be able to do things like this," says Zurl ahead of his Cuba challenge. Hide Caption 15 of 16 Photos: Ultra cyclist to cross Cuba in 57 hours Zurl says he will stay in Cuba after his ride to immerse himself in the country's culture. Hide Caption 16 of 16

"On the one hand it's really important that I have enough calories to do this ride, but it's hard to eat so much in only this time so we have to set protocol about how many calories I'm eating every hour," he says.

Was es nicht alles gibt 😀. #winterwonderworld #collectmomentsnotthings A post shared by Jacob Zurl (@jacobzurl) on Jan 29, 2017 at 5:57am PST

"It's important you don't have too much one hour and the next hour nothing. It has to be every hour the same calories.

"It's very important to take care of your stomach so that you don't have problems. Your body really is like a machine. It's completely amazing.

"When you're cycling for that long of course you get tired, but you can't drink five Red Bulls or coffees to stay awake because caffeine makes you go to the toilet and you will lose time."

Zurl, who works as a personal trainer to support his adventures, has been acclimatizing in Cuba this last fortnight, conserving his energy, easing off from the weekly 200-250km rides, living in the humidity that has forced him to readjust his finishing time from 55 to 57 hours.

The 90-minute strengthening routines at the gym three times a week have also stopped. The moment is nearly upon him.

"It's not a normal condition for cycling in Europe or America," says Zurl.

"You have to train a lot of years to be able to do things like this."

"I have many years preparing my body and also my head for things like this. There is no secret about it. It's cycling and if you have the passion to do things like this then you are also fast."