When avalanches claim a skier, or sharks attack a surfer, or a puff of unexpected wind dooms a wingsuit flier, it’s always news. Like these other “extreme” deaths, Worsley’s tragic end was reported and discussed around the world. There was a difference, though. There had been no avalanche, no large, hungry predator, no high-speed impact. He didn’t freeze to death, he wasn’t lost, and he still had plenty of food to eat. Though it may never be clear exactly what pushed him over the edge, he seemed, in essence, to have voluntarily driven himself to oblivion—a rarity that added a grim fascination to his demise. “In exploring the outer limits of endurance,” Britain’s Guardian newspaper asked, “did Worsley not realize he’d surpassed his own?”
In a sense, Worsley’s death seemed a vindication of the mathematical view of human limits. “The machinery of the body is all of a chemical or physical kind. It will all be expressed some day in physical and chemical terms,” Hill had predicted in 1927. And every machine, no matter how great, has a maximum capacity. Worsley, in trying to cross Antarctica on his own, had embarked on a mission that exceeded his body’s capacity, and no amount of mental strength and tenacity could change that calculation.
But if that’s true, then why is death by endurance so rare? Why don’t Olympic marathoners and Channel swimmers and Appalachian Trail hikers keel over on a regular basis? That’s the riddle a young South African doctor named Tim Noakes posed to himself as he was preparing to deliver the most important talk of his life, a prestigious honorary lecture at the annual meeting of the American College of Sports Medicine, in 1996: “I said, now hold on. What is really interesting about exercise is not that people die of, say, heatstroke; or when people are climbing Everest, it’s not that one or two die,” he later recalled. “The fact is, the majority don’t die—and that is much more interesting.”
To catch the ferry, Diane Van Deren needed to cover 36 miles in just over 8 hours. That would normally be no problem for the veteran ultra-runner—except, in this case, for the unforgiving terrain, the torrential rain and sumo-force winds left in the wake of Tropical Storm Beryl, and the fatigue and horrendous blisters accrued over the first 19 days and 900 miles of the Mountains-to-Sea Trail across North Carolina. Worse, Van Deren was startled to hear a “savage and malicious” roar from the darkness to her right. “What is that?” she yelled to her trail guide, Chuck Millsaps, the owner of a local outfitting company. It was just an airplane, he assured her—but to be safe, they strapped themselves together for mutual safety as they prepared to cross a wind-whipped bridge.
At stake in all the chaos was Van Deren’s attempt to set a new record for the 1,000-mile trail: if they missed the 1 P.M. ferry from Cedar Island to Ocracoke, the mark of 24 days, 3 hours, and 50 minutes would be out of reach. The fifty-two-year-old Coloradan was a connoisseur of the slow-drip torture of ultra-endurance challenges. She had pulled a 45-pound sled 430 miles across the frozen tundra to win the Yukon Arctic Ultra (second place was—well, no other woman finished); scaled the 22,838-foot peak of Aconcagua as part of a Mayo Clinic research expedition studying human limits; and racked up top finishes at grueling races of 100 miles or more around the world. Making the ferry, though, would require squeezing a relative sprint from her battered legs. She had been running from dawn to near-dawn for almost three weeks, sleeping one to three hours a night, barely pausing to let her North Face–supported crew team duct-tape her blistered feet and cram food into her mouth.
Fortunately, Van Deren had an advantage—or at least, a unique quirk that seemed to help her push past the corporeal limits that drag down most would-be ultramarathoners. At thirty-seven, she had undergone elective brain surgery to remove a golf-ball-sized chunk of her temporal cortex, the focal point of epileptic seizures that had plagued her, as often as two or three times a week, for years. The surgery successfully stopped the seizures but also left her with neurological deficits: poor memory, an impaired sense of direction, difficulty keeping track of time. A 2011 Runner’s World profile dubbed her “The Disoriented Express,” noting that “in races she must cover hundreds of miles, and yet often has no idea how long she has been running.” A significant handicap, you’d think—and yet it was only after the surgery that her racing career even started. To understand her extraordinary endurance, in other words, start with her brain.
The brain’s role in endurance is, perhaps, the single most controversial topic in sports science. It’s not that anyone thinks the brain doesn’t matter. Everyone, right back to A. V. Hill and other pioneers of the “body as machine” view, has always understood that the race is not always to the swift—particularly if the swift make bad tactical decisions, pace themselves poorly, or simply are unwilling to suffer. In that view, the body sets the limits, and the brain dictates how close you get to those boundaries. But starting in the late 1990s, a South African physician and scientist named Tim Noakes began to argue that this picture is insufficiently radical—that it’s actually the brain alone that sets and enforces the seemingly physical limits we encounter during prolonged exercise. The claim has profound and surprising implications, and the extent to which it’s true or false remains one of the most volatile flashpoints in exercise physiology, two decades later.
The particular tone of the controversy has as much to do with Noakes himself—an instinctive iconoclast who has been clashing with his scientific peers more or less continuously for four decades now—as with his ideas. “Tim is probably his own worst enemy,” says Carl Foster, the director of the University of Wisconsin–La Crosse’s Human Performance Laboratory and a former president of the American College of Sports Medicine, who counts Noakes as a friend. “He’s a very strong personality, and he gets these really neat, innovative ideas, but instead of saying, ‘Wow, I’ve found a better way to explain this,’ he says, ‘Everybody else is wrong.’” (Noakes, for his part, denies ever saying that everyone else is wrong. “Of course I believe they are wrong, but I am not about to tell them that,” he helpfully clarified in an email. “I just present what I believe is the truth.”) Either way, Foster acknowledges, if you want to challenge a century’s worth of textbook material, “maybe that stirring the pot is necessary.”
Noakes started out as a collegiate rower at the University of Cape Town, but his trajectory was altered one morning in the early 1970s when his rowing practice was canceled due to high winds. His teammates went home, but Noakes decided to stay and run around a nearby lake. After forty minutes, he was overcome by a feeling of euphoria—the classic but elusive runner’s high. Thanks in part to this quirk of brain chemistry, he quickly became hooked on the new sport, and ultimately shifted his professional interests from clinical medicine to running-related research. He went on to complete more than seventy marathon and ultra-marathon races, including seven finishes at South Africa’s famous 56-mile Comrades Marathon.
In the lab, meanwhile, his penchant for “paradigm-rattling,” as Foster calls it, emerged early. At a landmark gathering of sports scientists before the 1976 New York Marathon, at the height of the first jogging boom, most of the presentations focused on the incredible health benefits of running. Noakes, in contrast, presented the case report of an experienced marathoner who’d suffered a heart attack, puncturing the then-popular notion that marathoners were immune to clogged arteries. In 1981, he reported