era in the men’s 800 meter, mile, 5,000, and 10,000 meter races. For the three longer races, the pattern was startlingly consistent: after a quick start, the record breakers would settle into a steady pace until the final stages of the race. Then, even though they were running faster than they’d ever run before, and their oxygen-starved muscles were presumably awash in a sea of fatigue-inducing metabolites, they accelerated. Of the 66 world records in the 5,000 and 10,000 meters dating back to the early 1920s, the last kilometer was either the fastest of the race or the second fastest (behind the opening kilometer) in all but one. I was willing to attribute my own uneven pacing to incompetence—but these were the finest runners in history on the best day of their lives, which suggests that the pattern is more deeply ingrained than a mere pacing error.
In fact, there’s good reason to think that pacing is driven as much by instinct as by choice, according to Dominic Micklewright, a researcher at the University of Essex. Micklewright followed an unorthodox route to academia, going straight from high school to the Royal Navy, where he served as a diver on nuclear submarines for seven years, and then spending nine years as a police officer in London before studying sport and exercise psychology. His interest in pacing dates back to his training as a military diver, when he and the other trainees had to swim submerged to the other end of a 1,200-meter saltwater lake on Horsea Island, on Britain’s south coast, without using up their supply of air. “If they caught you breaching, you would get clobbered over the back of the head with an oar, or they’d throw in one of those underwater scare charges,” he recalls. With that incentive, you inevitably thought very carefully about the challenge of spending your energy—and oxygen—as frugally as possible.
In 2012, Micklewright had more than a hundred schoolchildren ranging in age from five to fourteen complete a battery of tests to assess their cognitive development, in order to slot them into one of the four developmental stages proposed by Swiss psychologist Jean Piaget; then the kids ran a race lasting about four minutes. The younger kids in the two lower Piaget stages opted for the unfettered sprint-and-then-hang-on-for-dear-life approach, starting fast then steadily fading. In contrast, the kids in the two higher Piaget stages had already adopted the familiar U-shaped pacing profile that world-record holders use: a fast start, gradual slowing, then a fast finish. Sometime around the age of eleven or twelve, in other words, our brains have already learned to anticipate our future energy needs and hold back something in reserve—a relic, Micklewright speculated, of the delicate balance between searching for food and conserving energy deep in our evolutionary past.
Not everyone buys Noakes’s argument that pacing patterns like the end spurt reveal the workings of a central governor. For example, it could be that you speed up at the end of a race because you finally tap into your precious but limited reserves of anaerobic energy, the high-octane fuel source that powers you in short races lasting less than a minute. But there are other hints that the finishing kick isn’t just physiological.
In 2014, a group of economists from the University of Southern California; the University of California, Berkeley; and the University of Chicago mined a massive dataset containing the finish times of more than nine million marathoners from races around the world spanning four decades. The distribution of finishing times looks a bit like the classic bell-shaped curve, but with a set of spikes superimposed. Around every significant time barrier—three hours, four hours, five hours—there are far more finishers than you’d expect just below the barrier, and fewer than you’d expect just above. Similar but smaller spikes show up at half-hour intervals, and there are barely perceptible ripples even at ten-minute increments. The cruel metabolic demands of the marathon, which inevitably depletes your stores of readily available fuel, mean that most people are slowing in the final miles. But with the right incentive, some are able to speed up—and it’s only the brain that can respond to abstract incentives like breaking four hours for an arbitrary distance like 26.2 miles.
A further curious detail from this dataset: the faster the runners were, the less likely they were able to summon a finishing sprint. Of the runners finishing near the three-hour barrier, about 30 percent were able to speed up in the final 1.4 miles of the race; 35 percent of those trying to break four hours sped up; and more than 40 percent of those trying to break five hours managed it. One possible interpretation is that, over the course of their long hours of training, the more committed runners had gradually readjusted the settings on their central governors, learning to leave as little as possible in reserve. Perhaps that’s another, slower way of achieving the run-in-the-present-moment strength that allows Diane Van Deren to race so close to her limits. I tried to trick myself into forgetting the last kilometer of my 5,000-meter races; Van Deren’s bittersweet gift is that she can forget without even trying.
Right from the start, the central governor proposal was highly controversial. After his 1996 speech, Noakes recalls, “people got very, very angry.” There were rebuttals and surrebuttals in a cycle that is still continuing, more than two decades later. In a 2008 article in the British Journal of Sports Medicine, Noakes argued that physiologists’ focus on VO2max had “produced a brainless model of human exercise performance.” Roy Shephard, an influential professor emeritus at the University of Toronto, shot back with an article in the journal Sports Medicine in 2009 titled “Is It Time to Retire the ‘Central Governor’?” Following a further exchange, Shephard concluded, “In the parlance of my North American colleagues, the time may now be ripe for proponents of the hypothesis to ‘Put up or shut up.’”
If anything, the controversies swirling around Noakes have increased since his retirement from the University of Cape Town in 2014. His book on hydration, Waterlogged, accused most of the world’s leading hydration researchers, including former colleagues and collaborators, of selling out to the commercial interests of sports-drink makers. He is now a vocal proponent of low-carb, high-fat diets for both health and athletic performance, leading him to disown the chapters he wrote on nutrition and carbohydrate loading in Lore of Running and earning him a disciplinary hearing that threatened to revoke his medical license after he tweeted advice to a breastfeeding mother about weaning babies onto a low-carb, high-fat diet.
As these other battles rage, the central governor controversy has to some extent faded into the background. With their own retirements on the horizon, it’s clear that the older generation of physiologists—Noakes’s peers—will never be convinced. On the other hand, says American Society of Exercise Physiologists cofounder Robert Robergs of Noakes’s influence, “most of the younger breed of exercise physiologists, in which I would group myself, recognize that, boy, some of his challenges are correct.” Whether the brain plays a role in defining the limits of endurance is no longer in doubt; the debate now is how.
One way to answer that question would be to peer inside the brain during strenuous exercise—a task that, until recently, was completely impossible. With advances in brain imaging, it’s now just very, very difficult. Functional magnetic resonance imaging, or fMRI, allows researchers to observe changes in blood flow to different regions of the brain with great spatial precision, but can’t capture changes that occur in less than a second or two. You also have to remain perfectly still inside the bore of a powerful magnet—a restriction that presents serious challenges for exercise studies. During my visit to Cape Town, Noakes showed me video of a Rube Goldberg–esque contraption, developed by collaborators in Brazil, that allows subjects to pedal an externally mounted
