Climbing Mount Everest is at the top of many people's bucket list.
But while most take two months to reach the top, scientists have revealed the debilitating training schedule of a man who has scraped the world's highest mountain twice in one week.
Kilian Jornet Burgada, now 29, set a world record in May 2017 when he approached the 29.028ft (8.848m) climb in just 26 hours and 31 minutes, just turned around and did it all over again.
The ultra-marathon champion set a new record for speed when he managed to complete the climb with an astounding speed of 1148 feet (350 m) per hour, all without oxygen or ropes.
But researchers warn that the performance is not attainable for most, with Mr Burgada being forced into a low-oxygen tent for four weeks and traveling through the Alps for 100 hours to prepare for the challenge.
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Kilian Jornet Burgada scaled the Everest twice in just one week. He is depicted during the trek
Kilian Jornet Burgada set a world record in May 2017 when he scaled up Everest in 26 hours and 31 minutes, only to reverse and do it again. It will be presented on 13 October 2013 on the Italian TV program Che Tempo Che Fa and close to the Sports Cultura Awards 2013 in Barcelona
Mr. Burgada climbed from the Rongbuk Monastery in Tibet to the summit, via the base camp, at 29,028 feet in 26 hours and 31 minutes. A stomach virus forced him to rest for a few days at the Advance Base Camp at an altitude of 21,325 feet from his descent. He then climbed to the top in 17 hours
Mr. Burgada was forced to live in a low oxygen-rich tent for four weeks and spent 100 hours in the Alps preparing for the challenge (it is unclear on which mountain he is pictured)
Mr. Burgada's training schedule was led by Dr. Gregoire Millet, associate professor in the physiology department at the University of Lausanne.
The ambitious hiker, who grew up in a hut in the Pyrenees, first had to get used to the harsh conditions of Everest by sleeping in an oxygen tent in his current hometown in Norway.
The tent was under pressure to simulate the atmosphere at the top of Mont Blanc, which is about 15,880 feet (4,810 m) above sea level, The Telegraph reported.
During the day, his tough regime combined & # 39; as usual & # 39; with high-intensity running training, according to a case report published in the International Journal of Sports Physiology and Performance.
These included him wearing a mask that delivered oxygen at concentrations similar to those found at more than 19,685 feet (6,000 m) above sea level.
After a month, his & # 39; wrist saturation & # 39; from 70 percent to 85 percent.
Pulse saturation measures how much oxygen is in someone's blood. High levels are needed to ensure that our muscles, brains, and other organs function as they should.
Mr. Burgada initially had a lower than average level, with lectures below 90 percent considered inadequate, according to the Mayo Clinic.
After this & # 39; gymnastics training & # 39; Mr. Burgada was exposed to & # 39; real & # 39; hypoxia when he trained in the Alps for 100 hours. This combined low oxygen with low ambient air pressure.
Ready for the Himalayas, he left the Rongbuk Monastery in Tibet on May 20.
His heavy training regime combined with & # 39; as always & # 39; with intensive training. These included him wearing a mask (pictured) that delivered oxygen in concentrations similar to those found at more than 19,685 feet (6,000 m) above sea level. He also lived in an oxygen tent
Only 26 hours and 31 minutes later he reached the top. There is no existing record for a climb from Base Camp – which is 5,364 m) – to the top, making this the fastest known time, the British Mountaineering Council reported.
Burgada even measured the highest speed ever recorded while climbing between 20,669ft (6,300 m) and 27,559ft (8,400 m) at 1,148 feet (350 m) per hour.
& # 39; This case study reports the preparation for the most remarkable performance ever performed at extreme heights & # 39 ;, the researchers wrote.
Mr. Burgada intended to climb Everest & # 39; s Norton or Hornbein Couloirs, but was forced to take the longer, though & # 39; easier & # 39 ;, Normal Route due to icy conditions.
But the mountaineer still withstood 37 mph (60 km / h) wind and developed a stomach worm that forced him to stop every 32 feet (10 m).
Due to his poor health, Mr. Burgada was too ill to return to base camp after climbing and to rest for a few days at Advance Base Camp, or Camp 2, at 6,500 m (21,325 feet). From there he ventured to the top again within 17 hours.
But Mr Burgada did not succeed in reaching the record for this route, which was set by Christian Stangl, from Austria, in 2006 at 4 pm and 42 minutes.
Pictured on the tour, he achieved the & # 39; excellent performance & # 39; without oxygen or ropes
Mr. Burgada (pictured on the expedition) planned to climb Everest & # 39; s Norton or Hornbein Couloirs, but was forced to take the longer, albeit & # 39; easier & # 39 ;, Normal Route due to icy conditions
Mr. Burgada (photo on the right, companion unknown) also has the record for the fastest known ascent and descent of Denali, Matterhorn and Mont Blanc. He even ran up Mount Blanc in five hours in shorts, under which he stopped to help a companion who fell into a crack
For those who want to achieve a comparable performance, the researchers first recommend that you live & # 39; high, train low & high & # 39; in terms of oxygen exposure.
Ambitious hikers then have to withstand both low oxygen and low air pressure at low altitudes for a better translation of the benefits.
But the researchers warn that the training regime may not work for those who are less fit than Mr. Burgada.
Like the scales of Everest, he holds the record for the fastest known ascent and descent from Denali, Alaska; and the Matterhorn and Mont Blanc, both in the Alps.
He even ran up Monte Blanc in shorts in a short time, including stopping to help a companion who fell into a crevass.
Burgada also shuns taking food during his trips, opting instead for & # 39; taking what nature gives & # 39 ;.
He has also won numerous ultra-marathons. These include Ultra-Trail du Mont-Blanc, which is 171 km long and has a 33,000 feet (10,058 m) altitude gain.
Mr. Burgada was even held for an hour at the last checkpoint of the Ultra Trail because no one believed he could have completed the endurance test so quickly, The Times reported. But he still beat the runner-up with 60 minutes.
The investigators issued Mr Burgada's case report to silence critics who claimed that his Everest achievements proved not to be conclusive.
American climber Dan Howitt claimed that he & # 39; was chronically evaded from obtaining basic summit verification and time verification & # 39 ;.
Later investigations into Burgro's GoPro camera confirmed his first ascent, but not the second.
He has recently proven his athletic abilities by going up 24,000 m in alpine skiing in just one day, corresponding to 2.7 Everests.
Burgada is now looking for & # 39; short expeditions & # 39; to prevent him from spending too much time outdoors.
He has also won numerous ultra-marathons. These include Ultra-Trail du Mont-Blanc, which is 171 km long and has a 33,000 feet (10,058 m) altitude gain. Tour shown unknown
Mr. Burgada (pictured on an unknown journey) is now looking for & # 39; short expeditions & # 39; to prevent him from spending too much time away from his home in Norway
HOW CLEAN SHOULD EVEREST BE CLIMB?
Everest is & # 39; the world's highest mountain and lies along the border of Nepal and Tibet.
The altitude is a controversial topic, with different measurement methods that produce changing results.
However, the general consensus is that Mount Everest is 29,029ft (8,848m) above sea level.
Sir Edmund Hillary and Tenzing Norgay were the first to reach the summit on 29 May 1953 as part of the British expedition led by Lord John Hunt.
From February 2014 Everest was scaled 6,871 times among 4,042 mountaineers.
Tragically, 265 people died while climbing the Everest between 1922 and 2014.
On April 18, 2014, 16 aerial platforms were killed in the Khumbu Icefall under camp 1 when a block of glacial ice collapsed.
These employees often act as guides and carry tents and other necessities up the mountain for hikers.
Most expeditions take approximately two months.
Alpine Ascents recommends attending at least one year of training specifically to climb Everest.
& # 39; You will need to gradually increase your walking time, distance and gain in altitude (about 10 percent per week) to build your climbing-specific conditioning safely and effectively & # 39 ;, he says.
Those who hope to reach the top must also complete expeditions of more than 20,000 feet (6,096 m) in advance.
And have experience & # 39; handling equipment & # 39; and & # 39; deal with extremely low temperatures and extreme altitude & # 39 ;.
Almost everyone who climbs Everest uses a commercial shipping operator.
Prizes range from $ 65,000 (around £ 50,250) to $ 35,000 (£ 27,060). A tax of approximately $ 11,000 (£ 8,500) also goes to the Nepalese government.
And every climber must pay $ 600 (£ 460) to the Sagarmatha Pollution Control Committee.
All freight forwarders must have a helicopter and life insurance policy.