Most athletes would agree that lactic acid build-up in the muscles is the bane of all long-distance runners – but not American jogger Dean Karnazes. The 53-year-old has a rare genetic condition that rapidly flushes lactic acid from his system, allowing him to run indefinitely without ever experiencing a cramp or a seized muscle. The extreme runner has completed a marathon to the South Pole at -25C, and completed 50 back to back marathons in 50 days. He’s also jogged a whopping 350 miles in just 80 hours and 44 minutes, without any sleep!
When people exercise, glucose is converted into energy and a by-product of this reaction is lactic acid. As it builds up in the muscles, it causes cramps and fatigue, and signals the brain to stop. But in Dean’s case, he never receives those signals because lactic acid never builds up in his muscles. So he’s able to run for long distances over very long periods of time, giving him an edge in some of the toughest endurance competitions in the world.
“At a certain level of intensity, I do feel like I can go a long way without tiring,” Dean said, speaking to The Guardian. “No matter how hard I push, my muscles never seize up. That’s kind of a nice thing if I plan to run a long way. To be honest, what eventually happens is that I get sleepy. I’ve run through three nights without sleep and the third night of sleepless running was a bit psychotic. I actually experienced bouts of ‘sleep running’, where I was falling asleep while in motion, and I just willed myself to keep going.”