"Liquid Mountaineering"... was later revealed to be a hoax.

"Liquid Mountaineering"... was later revealed to be a hoax.

Easy as it is to poke fun at those who believe they can defy nature, physics and – it must be said – common sense, there are seemingly superhuman feats that would make even the coldest scientists catch their breath.

Marvelling at how we can teeter at the edge of human capability is big business; Ripley's Believe It or Not! franchise and Guinness World Records are as much about entertainment as they are achievements. Are these feats of endurance and strength borderline miracles, or mere stunts with somewhat deflating scientific explanations?

For all the empowering marketing mantras pumped out by Nike, Adidas and Hi-Tec, it turns out there are some things you shouldn't, or simply can't do.

Chad Netherland holds the most strength-based Guinness Records in the world.

Chad Netherland holds the most strength-based Guinness Records in the world.

Running on water is one of them. The viral "Liquid Mountaineering" video was recently exposed as a Hi-Tec hoax. Their head of marketing came clean: “People debated whether this could indeed be possible. We've seen entertaining attempts on YouTube. Whilst our shoes have amazing liquid repellency features, even we still can't walk on water … it was a well-intended hoax.”

Fire-walking is another. In July this year, 21 people were treated for burns after walking over hot coals at a Tony Robbins motivational seminar.

Then there are those who claim their superhuman feats are close to miraculous.

Five times Guinness World Record holder Dan Meyer has swallowed 21 swords simultaneously and one heated to 1500 degrees.

Five times Guinness World Record holder Dan Meyer has swallowed 21 swords simultaneously and one heated to 1500 degrees.

Five times Guinness World Record holder Dan Meyer has swallowed 21 swords simultaneously and one heated to 1500 degrees, which almost fried off his lips and baked him from inside out. “The mind can push the body past previous limitations,” Meyer told me. “Swallowing a sword always seemed 99 per cent impossible – until I changed my focus to the 1 per cent that WAS possible.”

He says that the conditions must be right, and can be biologically explained: “Repress the gag reflex, open the epiglottis, repress the peristalsis, relax the oesophageal sphincter, slide through the diaphragm, repress the stomach retch reflex, slide past the liver and kidneys.” Apologies if you've just eaten.

How does this entertainer respond to the suggestion that his act is more of a stunt than a remarkable feat of human endeavour? “I enjoy that audiences believe sword swallowing is just a cheap magic 'trick'. But what I do is all very dangerous and real.”

Meyer sees himself as a messiah of the miraculous: “I've found my purpose in life - to inspire audiences to do the impossible in their lives. I love my job.”

Fred Burton is another record holder who claims he miraculously achieves the unachievable. Burton hold records for the furthest distance a car has been pulled by teeth (30 metres in 29 seconds); the most concrete blocks smashed on one's head (16); and the most weight thrown with teeth (66 pounds thrown 5 foot).

A “well-trained body and sound mind” are essential, he says. But “some things I've done are impossible to explain. My doctor says my make-up is different. I work on the edge of possibility.”

Chad Netherland holds the most strength-based Guinness Records in the world, including restraining aircraft from taking off. He also believes that the biggest miracle is the power of the mind.

“You can accomplish anything you set your mind to," he says. "Most people aren't mentally prepared to go the extra distance to reach their goals. When it hurts they allow pain and fear of failure to rob them of success.”

He's also insistent that trickery plays no part: “Laying on a bed of spikes and having 1000 pounds of concrete placed on you in front of a live audience? It's hard to fake that. It's based on training and determination — not trickery. The only trick is being so good that it looks easy.”

As well as tearing phone books in half and bending steel bars over his head, James Heathers researches the science behind this; his PhD in autonomic physiology measures the body's unconscious control systems. His take on superhuman feats differs from those of others I spoke to. He demystifies the seemingly impossible: “It's all science, the whole way down to the ground. Everything that seems impossible contains one fact you don't realise, one secret. Fire walking works because wood is a poor thermal insulator. Lying on a bed of nails works because your mass is distributed, likewise lying on broken glass. The physics of these principles is how people like me come up with these feats in the first place.”

Marcello Costa, Professor of Neurophysiology at Adelaide's Flinders University says: “Let's rejoice individuals who do extraordinary things without creating magical monsters. They're still humans. Please avoid this ancient and wrong term of 'mind over matter' and abandon the word 'miraculous'!”

Perhaps these remarkable men have different genes. Maybe their minds are more malleable. Or, as the cynical argue, it could be the Wizard of Oz complex – a seemingly formidable figure who is actually a small man with a large megaphone. Either way, the wow-factor comes from dedication to doing the unimaginable.

But it was sword-swallower Dan Meyer's words that had the most profound effect on me: “As a child, I grew up filled with fear — fear of water, sharp objects, public speaking, rejection and failure. I suffered from low self-esteem and inferiority complex. I was badly bullied. Because the bullies never let me play in their sports games, I wanted to do things other kids couldn't — I wanted to be a superhero. I learned juggling, stilt walking, fire-eating, glass eating and eventually sword swallowing.

"Today those kids aren't laughing any more.”