For most ordinary folks, completing a marathon is about as extreme as things go when it comes to feats of stamina. Occasionally though, there are some athletes who take the idea of endurance to a whole new level. Here are 7 notable feats of stamina that redefine the limits of human potential.

The Longest Brawl in Boxing

Today we associate the high-profile sport of boxing with huge purses and judges who qualify every single punch. However, boxing’s history as a sport grew out of bare-knuckle fighting, where the only way to determine a winner was literally by the last man standing. Interestingly, there were rarely any deaths in boxing until gloves came in, as punching a bony skull with knuckles tends to end up damaging the puncher's hands more than the opponent. With more body hits, fights could go on much longer, providing a true test of physical and mental stamina.

The ultimate Battle Royale of boxing took place on April 6, 1893. Showing severe tenacity to never give up, boxers Andy Bowen and Jack Burke duked it out for unthinkable 111 rounds. The two pugilists pummeled each other for a total of seven hours and 19 minutes, at which point the referee finally called a stop to the fight and ruled it a draw. The epic battle certainly took it’s toll on the fighters, with Burke having to retire after breaking all the bones in both of his hands. 

The Longest Single Breath Underwater

In an incredible demonstration, David Blaine set a Guinness World Record underwater live on The Oprah Winfrey Show. The illusionist held a single breath continuously for a whopping 17 minutes and four seconds. Unfortunately for him, this inspired German veteran diver Tom Sietas, one of the world’s leading free drivers, to top the feat with an achievement of 17minutes and 19 seconds. Sietas has an incredibly high-lung capacity, also holding world records deep diving without the aid of oxygen tanks.

Still, as a street magician with no diving or athletic background, Blaine’s record setting baffles the imagination. Even without superior physical fitness, he demonstrated that mind over matter can push the body beyond what was even thought possible. 

2 Month Swim Across the Atlantic

Benoit Lecomte is one of the greatest long-distance swimmers to have ever lived. The Frenchman’s most impressive feat was being the first person to conquer the Atlantic Ocean in 1998.  Using doggy paddle without aids, he swam 8 hours per day for 73 days. This took him from Massachusetts to Brittany, covering a staggering 3,716 miles of treacherous waters, including relying on a tail boat to ward-off sharks.  

The Ultimate Non-Stop Run

Dean Karnazes is considered the best endurance runner ever, with a prolific range of accomplishments from a young age. His phenomenal abilities are partly attributed to an unusual lack of lactic acid buildup in his system while fatigued.

Probably his greatest run to date took place on October 18, 2005, when the Californian pulled off a nonstop 350-mile run around the San Francisco Bay area. This involved an incredible 80 hours on-the-go at a relentless pace.  

Highest Climbs Without Oxygen

Italian alpinist Karl Unterkircher was both a highly skilled climber a truly elite athlete. In 2004 he accomplished for the first time the summiting of both Mount Everest and K2, without the aid of oxygen. These are not only the two highest peaks on Earth, but are also known to be dangerous, claiming numerous climbers lives on a yearly basis.

Unterkircher’s oxygen levels near the peaks was so low, that at times he almost passed out just from the effort of maintaining his breathing. This is known as the ‘death zone’, where the body literally starts consuming it’s own cells because the air is too thin to actually support respiration. 

The Most Brutal 2 Days of Cycling

The UK has a famous bike ride called Land’s End to John o’Groats, which traverses the whole length of Great Britain from top to bottom. For most serious cyclists, this 874 miles course takes two weeks of long daily rides to complete. However, in 2001, cyclist Gethin Butler shocked the cycling world by completing the whole journey in just two days. The extreme cyclist pedaled at a blistering pace for 22 hours each day. In similar fashion, Butler has also cycled 1,000 miles in two days, seven hours and 53 minutes. 

The Marathon Tennis Match

The most recent feat on this list took place in the 2010 Wimbledon championships. Instead of the typical 3-4 hours to complete a tournament tennis match, John Isner and Nicolas Mahut played a whopping 11 hours. This was by far the longest ever contest in professional tennis history, with a total of 183 games completed over three days.

In an incredibly competitive and closely fought match, this included a gargantuan single set with countless tie-breakers, lasting over eight hours. 28 ball boys were needed, and the players had to persevere through brutal cases of tennis elbow. In the end Isner narrowly took the match.

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