Most athletes are known for pushing and exceeding their perceived limits, but every athlete does, indeed, have a limit that physiologically cannot be exceeded. This limit is scientifically defined as the human body’s lactate threshold. Every athlete’s lactate threshold is different, unless, of course, your name is Dean Karnazes, who doesn’t have one.
Dean Karnazes, now known as a world-renowned endurance runner, began distance running at an early age. When Karnazes was in high school, he began to set himself apart from his classmates and competitors with his absurd ability to run inhumanly long distances. At a charity fundraiser, Karnazes reportedly ran an astounding 105 laps around his high school track, while his classmates were only able to run 15 laps at most. Karnazes eventually stopped running altogether after high school, and, having an epiphany on his 30th birthday, started running into the night. He stopped over 30 miles later.
Years later, Karnazes sent to a testing center in Colorado where they performed a series of tests which soon discovered that Karnazes was biologically different than any other human being. “First, they performed an aerobic capacity test in which they found my results consistent with those of other highly trained athletes, but nothing extraordinary. Next, they performed a lactate threshold test. They said the test would take 15 minutes, tops. Finally, after an hour, they stopped the test. They said they’d never seen anything like this before,” he told The Guardian.
“If you take a high-level runner and you train that guy for a long time, his cardiovascular system will improve until a certain point where it will be very difficult to improve it further, as it’s determined by the heart and the blood vessels. So if you carry on training that guy, you will not improve his aerobic capacity but his performance will still improve, because the lactate threshold is not limited by the cardiovascular system – it’s determined by the quality of the muscles,” says Laurent Messonnier of the University of Savoie.
Since Karnazes discovered his superpower, he has completed some of the most grueling endurance events in the world, from the Marathon des Sables to the inaugural South Pole Marathon, in which temperatures reached as low as -25C. Karnanzes says he has never experienced a cramp from running in his entire life. “At a certain level of intensity, I do feel like I can go a long way without tiring. 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,” he said.
In 2006, Karnazes completed the very heavily publicized Endurance 50: 50 Marathons in 50 States in 50 Consecutive Days. The title says it all as Karnazes completed his first marathon in St. Louis, Missouri on September 17th, 2006 (Lewis and Clark Marathon) and his last in New York City, New York on November 5th, 2006 (New York City Marathon). While only eight of these races were held as official marathons, 42 of his marathons were held on actual marathon courses, such as the Boston Marathon’s official course, out of season.
Now 53, Karnazes is still running. He has written/coloborated on several books including Ultramarathon Man: Confessions of an All-Night Runner, 50/50: Secrets I Learned Running 50 Marathons in 50 Days, and Run: 26.2 Stories of Blisters and Bliss, as well as being the subject of 60 Minutes and several ESPN features. Among many racing awards and honors, Karnazes is a three-time Endurance Athlete of the Year, an Adventure Hall of Famer in Men’s Journal, and won an ESPN ESPY Award for “Best Outdoor Athlete” in 2007.