Meet the man who can run 3 days-3 nights straight without stopping!

American ultra-marathon runner Dean Karnazes has revealed that he can run for three days and three nights without stopping or even getting a blister.

The 51-year old, who is the author of 'Ultramarathon man: Confessions of an All Night Runner', has participated in some of the toughest marathons including running to the South Pole in -25 degrees Celsius temperature and claims that he's never ever experienced any form of cramp or muscle fatigue, the Courier Mail reported.

However, according to the Guardian, Karnazes had recently admitted that after three days running, he tends to feel a bit "sleepy and psychotic" and has experienced bouts of 'sleep running', where he would fall asleep while running.

According to scientists in Colorado, the ultra-marathon runner has an extraordinary high lactate threshold, but Karnazes reckons that his low body fat, low sweat rate, highly alkaline diet and low exposure to environmental toxins are the secret behind his running abilities.