The Sports Gene: Inside the Science of Extraordinary Athletic Performance

by David Epstein

  Some of the world’s greatest endurance athletes, too, seem almost to come out of the box in better shape than their peers. Athletes like Chrissie Wellington.

  •

  Wellington, a thirty-six-year-old British triathlete, made her name in Ironman races: a 2.4-mile swim, followed by a 112-mile bike ride, all before a full 26.2-mile marathon run.

  She is the greatest female Ironman triathlete ever, and not by a little. In thirteen iron-distance races, including four Ironman world championships, she never lost. In July 2011, Wellington turned in one of the more outlandish performances in endurance sports history: she finished a race in Germany in 8 hours, 18 minutes, and 13 seconds; more than half an hour faster than the world record prior to Wellington’s appearance in the sport in 2007. Her time would have placed her ahead of all but four men in that particular race.

  By her own admission, Wellington was not interested in devoting herself to fierce sports practice when she was a child in the tiny village of Feltwell in eastern England. Her childhood passion was environmentalism. “I was the kid organizing neighborhood recycling,” she says. Wellington did play sports, but “my aim in school was to get the best grades that I possibly could, and I used sports more just for fun.” So she tried a bit of everything: running, field hockey, netball, and she swam for the local Thetford Dolphins.

  When Wellington was fifteen, her parents realized they had an aquatic talent in their living room. Here’s how Wellington recalls the conversation: “My parents said to me, ‘Look, you’ve got potential in swimming, do you want to join the big swimming club that’s an hour away and we’ll drive you every morning? Or, it’s your major exams coming up when you’re sixteen, do you want to focus on that?’ And I said, ‘Look, I’d rather stay with my local swimming club, not take it so seriously, and focus on my exams.’ And that’s the choice I made when I was younger.”

  Wellington’s academic focus served her well. She went on to graduate with honors from the University of Birmingham in 1998 before traveling the world and then starting on her master’s degree in international development at Manchester University. In 2002, Wellington took a job at the British government’s Department for Environment, Food, and Rural Affairs, or DEFRA. For two years, Wellington worked to implement development projects in impoverished countries, and she helped draft the official UK policy for the postconflict reconstruction of Iraq. In the meantime, she had started recreational running. When she entered her first marathon, she shocked herself by finishing in three hours when her expectation had been 3:45. She was intensely passionate about her job as a civil servant, but by 2004 Wellington had tired of the bureaucratic tango it took to push incremental policy changes. She burned to have a tangible impact. So she moved to Nepal to work on a sewage sanitation project in an area ravaged by civil war. There, in the Himalayan mountains, was born the inspiration for her professional triathlon career.

  Wellington had no road biking experience—she was twenty-seven the first time she sat atop a road bike—but in May 2004, just before she left for Nepal, a friend goaded Wellington to try an amateur super-sprint-length triathlon. That’s a quarter-mile swim, a six-and-a-quarter-mile bike, and a one-and-a-half-mile run. Wellington borrowed a shabby road bike that she says was “black and yellow and looked like a bumblebee.” Unlike the serious competitors, Wellington did not have clip-in shoes for the bike, and midway through the race she got her shoelace tangled in the gears and nearly fell. Nonetheless, she finished third and had a blast. So Wellington did two more super sprint triathlons, and won both times. When she landed in Nepal, she bought a bike.

  In Nepal, Wellington would cycle with friends some mornings. Right away, she noticed, “I could just go and go and go all day.” During a two-week holiday from work, Wellington and a group of friends traveled to the Tibetan capital of Lhasa and then biked eight hundred miles through the Himalayas back to Kathmandu.

  Wellington had been living at an altitude of around five thousand feet in Kathmandu for eight months, so she had a degree of altitude acclimation, but much of the holiday ride was done above fifteen thousand feet—it topped out at Everest Base Camp, near eighteen thousand feet—where the air is so thin that unacclimatized folk have trouble walking, much less riding. That wasn’t a problem for some of the men who rode alongside Wellington. Not only were they experienced cyclists, they were Sherpas, native Nepali people who make their living shepherding climbers up Mount Everest. “Their technical skills were far superior to mine,” Wellington says, “but I could hold my own climbing up the hills and the mountains.”

  “When I returned to Britain from Nepal [in late 2005],” she says, “I was determined to give triathlon a good shot. I still had no idea of being professional, though.”

  In February 2006, shortly after her return, Wellington was at a wedding in New Zealand and “got roped” by friends into entering a 151-mile running, cycling, and kayaking adventure race through the Southern Alps. Wellington’s lifetime of kayak training consisted of a crash-course tutorial the previous month. Despite capsizing several times in the kayak leg of the race, she placed second. In September, juggling training and a full-time job, Wellington won an amateur triathlon world championship title. Five months later, in February 2007, she turned pro.

  In October that year, despite having trained exclusively for shorter triathlon races, Wellington entered the Ironman World Championship as a virtual unknown to her competitors. Her anonymity lasted through the early afternoon of October 13, 2007, when she arrived at the running portion of the world championship race two minutes ahead of the closest woman. “I kept expecting the other athletes to be stronger and come up and pass me,” Wellington says, “but the gap was just growing.” By the finish line, the gap had grown to five minutes.

  The British Triathlon Federation hailed the win as “a remarkable feat, deemed to be a near impossible task for any athlete racing as a rookie at their first Ironman World Championships.” Wellington bested athletes like second-place finisher Samantha McGlone. In each of the five previous years, while Wellington was helping bring drinking water to third-world countries, McGlone had been a member of the professional Canadian National Elite Triathlon Team. She had already competed in triathlon at the 2004 Athens Olympics, and, unlike Wellington, was actually deliberately practicing to race the Ironman distance. “We all have talents,” Wellington says. “And sometimes those talents are hidden and you have to dare to try something new or you might not know what you’re good at.”

  By the time Wellington retired in December 2012—ending a career that was five years from start to finish—triathlon-as-after-work-hobby was a receding memory. As a professional, Wellington trained zealously. Six sessions each of swimming, biking, and running per week and six-hour training days were not uncommon, not to mention the massage afterward and meticulously planned meals and sleep. She never stopped improving throughout her career and her best work may still have been ahead. But it was her rapid rise that was most startling.

  When asked what her weak spot was relative to her competitors, Wellington is quick to point to her swimming, the discipline in which, interestingly, she has the deepest experience.

  •

  In the York University study, 6 out of 1,900 men were in the naturally fit fraternity. That sounds rare at first blush, but 6 out of 1,900 suggests that most large high schools have a few naturally fit boys, and, if the results can be extrapolated to women, there are more than 100,000 naturally fit people in the United States between the ages of twenty and sixty-five. Looking at it this way, it’s reasonable to wonder whether every professional endurance athlete in history might not have started as a member of the naturally fit fraternity.

  The school fitness test—like the one that set Nancy Tinari on an Olympic path—is not a terribly uncommon venue for the identification of future world-beaters. Meb Keflezighi, the Eritrean-American who in 2009 became the first American man to win the New York City Marathon
in twenty-seven years, initially got a sense of his endurance prowess during the mile run in seventh-grade gym class in San Diego. “I just ran hard because I wanted that A; I had no idea of strategy or pace,” Keflezighi writes in his autobiography, Run to Overcome, of the 5:10 mile he clocked on no training. The gym teacher phoned the San Diego High School cross-country coach and told him, “We’ve got an Olympian here.” Indeed. Keflezighi went on to win the silver medal in the marathon at the 2004 Olympics in Athens. “A PE class had turned my life around,” he writes, “though I didn’t know it at the time.”

  Andrew Wheating, a twenty-five-year-old American and one of the nation’s top milers, did not run his first track race until his senior year at tiny Kimball Union Academy in Meriden, New Hampshire. His running career was kick-started when he ran a five-minute mile as part of a conditioning drill before his junior-year soccer season. Apparently sensing that his athletic future lay on the track and not the pitch, Wheating’s soccer coach suggested he switch to cross-country. Wheating did so and earned a track scholarship to the University of Oregon, a powerhouse running program. The summer after his sophomore year at Oregon—his third track season ever—Wheating made the U.S. Olympic team in the 800-meters. Two years later, at the end of the 2010 track season, Wheating ranked fourth in the world in the 1,500-meters with a time of 3:30:90, equivalent to a mile time under three minutes and fifty seconds.

  Cuban runner Alberto Juantorena, who in 1976 became the only athlete ever to win gold medals in both the 400- and 800-meters, had been an aspiring basketball player in 1971 when the national team basketball coach suggested he switch to running. “Thanks for the offer, but no, I’d rather not,” Juantorena insisted. “You know basketball is my life.” To which the coach responded: “We’re sorry, but it’s already been decided that you will change sports. Starting tomorrow, you are a runner, not a basketball player.” Juantorena made the Munich Olympics the very next year.

  But it could also be that some naturally fit people are not like Wellington or Wheating, but are instead like the low responders in the HERITAGE study, in which case they would not improve rapidly with training. (Bouchard’s research group also has DNA from three hundred endurance athletes with very high VO2max scores. Based on their gene variants, unsurprisingly, none of them is predicted to be at the low end of the responder spectrum.) Based on his data, Bouchard estimates that between one in ten and one in twenty people start with elevated aerobic capacity—though not nearly as high as the naturally fit six—and between one in ten and one in fifty people are high aerobic responders. “The probability that a person will be highly endowed and highly trainable is the product of those two probabilities,” Bouchard says. “It’s not pretty. It’s between one in one hundred and one in one thousand.”

  The ultimate combination, of course, would be a person who starts with a highly elevated aerobic capacity and has a rapid training response. It is very difficult to identify those people before they start training, as athletes are not normally subjected to lab tests until they have already accomplished something. Science is far better at looking at an elite athlete and retrospectively suggesting why that individual is succeeding than in finding someone who might succeed before he or she has started practicing—and had a chance to respond to training—and then following them.

  But there was a bit of unique and relevant science done by Dr. Jack Daniels, an exercise physiologist, former U.S. Olympic pentathlete, and one of the world’s most well-respected endurance coaches. Decades ago, Daniels tracked one Olympic runner over the course of five years, testing him on all manner of biological traits at least every six months. When fully trained, the runner had a VO2max about double that of an average, untrained but healthy man. The third year of the study, however, brought an unexpected research problem: the athlete got sick of competing. The pressure of expectations and the ceaseless slog and drudgery of interval training got to him. The runner was less than halfway through a race at the national championship when he simply stepped off the track and refused to run another step for an entire year. More than a year and a half passed before he really got serious about racing again.

  Instead of giving up on his research, Daniels tested the athlete during his year of lazing around. An athlete who stops training can within weeks lose more than 15 percent of the VO2max he built up. The runner’s VO2max had fallen 20 percent by the time Daniels tested him. In the absence of training, the Olympian’s aerobic capacity lined up exactly with the naturally fit six from the York University study. (Decades later, this would become a familiar pattern to Daniels. In 1968, for his Ph.D. dissertation, Daniels tested twenty-six elite runners, fifteen of whom went on to the Olympics. When he retested them in 1993, even those who had stopped running many years earlier and were overweight maintained a VO2max much higher than normal men. Said Daniels, in an interview with Flotrack: “Even the ones who hadn’t [continued to] run pretty well proved the genetic characteristics.”)

  After a year of mental convalescence, the runner started jogging with his wife. And with the Olympics approaching, his fire for full-time training was reignited. As the runner gradually increased his training intensity, he quickly regained, essentially precisely, the 20 percent of his aerobic capacity that he had lost during his fallow period.

  From a physiological standpoint, what Daniels chronicled over five years was in line with the results of a seven-year study of male, junior Japanese distance runners. The boys were selected for the study because each had won a middle- or long-distance event at the Japan Junior Championship. The study then followed the boys as they trained assiduously from the ages of fourteen to twenty-one for two hours each day, five or six days a week. Their aerobic capacities started at almost the identical level as Daniels’s Olympian during his period without training—around the same level as the naturally fit six. Over the course of their years of training, the boys all improved, but naturally divided into two groups: study group I, which saw an average aerobic capacity increase of 13 percent; and study group II, with boys who hit a plateau of 9 percent aerobic improvement—as well as a plateau in race time improvement—by age seventeen. Each of the boys in the latter group, having ceased to improve, quit running altogether after age seventeen. There may have been, in effect, a form of natural self-selection that left in the competitive population (and working toward their 10,000 hours) only those boys who continued to improve. That is not to say the boys who continued competing were just lucky. The study suggests that the more potential to improve the boys had, the longer and harder they had to work to reach it. But the ability to improve may have kept them in the sport and dedicated to training.

  So the group I Japanese boys appeared, like Daniels’s Olympian, to have a high baseline aerobic capacity as well as the ability to improve more than their peers. But Daniels’s Olympian improved even more, while some of his peers, like the group II Japanese boys, flat-lined and went off to follow other interests. From the looks of it, Daniels’s Olympian both had a naturally high aerobic fitness and was a high responder to training.

  Incidentally, the Olympian was Jim Ryun.

  6

  Superbaby, Bully Whippets, and the Trainability of Muscle

  The baby boy was born around the turn of the millennium, and it was the twitching that grabbed the nurse’s eye. Sure, the boy was slightly on the heavy side, but nothing jaw-dropping for the nursery at Charité hospital in Berlin. But those jitters. The little ticks and shudders that started just a couple of hours after he was born. The doctors worried that he might have epilepsy, so they sent him to the neonatal ward. That’s where Markus Schuelke, a pediatric neurologist, noticed his pipes.

  The newborn had slightly bulging biceps, as if he had been hitting the womb weight room. His calves were chiseled, and the skin over his quads was stretched a bit too taut. Soft as a baby’s bottom? Not this baby. You could bounce a nickel off these glutes. Ultrasound examination of his lower body showed that the boy was beyond the
top of the baby charts in the amount of muscle he had, and beneath the low end of the charts in terms of fat.

  The boy was otherwise normal. The functioning of his heart was ordinary, and the jitters subsided after two months. Perhaps the baby was the Benjamin Button of bodybuilding, and would gradually lose muscle. Not quite. By the age of four, he had no trouble holding 6.6-pound dumbbells suspended horizontally at arm’s length. (Imagine toddler-proofing that household.)

  Monstrous strength ran in the family. The boy’s mother was strong, as were her brother and father. But her grandfather—he was acclaimed on his construction crew for unloading 330-pound curbstones from truck beds with his bare hands.

  Fully clothed, the boy did not stand out from his peers. You wouldn’t ogle his puerile pecs if you passed him in the street. But the muscles in his upper arms and legs were roughly twice the size of other boys his age. Double muscle. It reminded Schuelke of something.

  •

  In the early 1990s, Johns Hopkins geneticist Se-Jin Lee had begun searching for muscle in his lab on North Wolfe Street in Baltimore. Not the finished muscle tissue itself, but the protein scaffolding that builds it. The purpose of the search was to find treatments for muscle-wasting diseases, like muscular dystrophy. Lee and a group of colleagues targeted a family of proteins known as transforming growth factor-ß. They cloned genes that coded for the proteins and then set off like kids with new toys, trying to figure out what the heck each gene did.

  They gave the genes prosaic names—growth differentiation factor 1 through 15—and then bred mice that lacked working copies of each gene, one at a time, so they could see what would happen and thereby deduce each gene’s function. The mice without GDF-1 had their organs on the wrong side. They didn’t survive long. The mice without GDF-11 had thirty-six ribs. They, too, died quickly. But the mice without GDF-8 survived. They were freak show rodents of a different kind. They had double muscle.