Every Summer Olympics features a handful of superhumans the likes of Usain Bolt, Gabby Douglas and Michael Phelps. Rio will be no exception. With shows of supreme physical strength and grace, the standouts in the 2016 Games will sprint, flip and glide their way through a gauntlet of grueling events. They will captivate the crowds, smash records and, in all likelihood, leave Brazil with an impressive haul of gold.

But what, exactly, sets these superelite athletes apart? It has long been a matter of heated debate. Historically, experts and sports fans alike have believed that genes are primarily responsible for such extraordinary achievement: top athletes are simply born with superior physical traits that allow them to outperform everyone else. During the past three Summer Games, for instance, many analysts credited Phelps's stunning success in the pool—winning him a total of 22 medals—to his 80-inch “wingspan” and hyperflexible, flipperlike size-14 feet.

Since the 1990s, though, another school of thought has gained considerable traction—namely, the idea that inborn talent is not, in and of itself, enough to reach the highest echelons in sport. No matter how good someone is by nature, genuine expertise also demands certain psychological traits, as well as years of hard work and first-rate coaching [see “How to Coach Like an Olympian”]. Sports psychologists are finding, for instance, that the experience of overcoming major emotional challenges can sometimes instill extra resilience in young athletes and fuel their exceptional drive. Genes, meanwhile, make a difference in how much individuals respond to training in addition to shaping their baseline gifts.

“For a long time people believed either you had innate talent or you didn't,” says K. Anders Ericsson, a psychologist at Florida State University who coined the term “deliberate practice” for a training approach that involves goal setting, repetitions of component skills, mental rehearsals and immediate feedback—now seen as critical for elite athletes. His work, described in a new book, Peak: Secrets from the New Science of Expertise, debunks the idea of “naturals” who seem to come out of nowhere but have often just switched sports. “I've always found plausible alternative accounts that involve prior purposeful practice,” Ericsson says.

Is it his drive, his “wingspan” or the combination that has propelled Michael Phelps to win 22 Olympic medals? CREDIT: JEFF HAYNES Reuters Pictures

In truth, going for gold probably always takes huge amounts of genetically bestowed potential, mental toughness and first-class training—as well as lots of luck to avoid injury, to connect with the right coach, and to find the best resources and support.

Fast, Faster, Fastest

Jerry Baltes, head cross-country and track coach at Grand Valley State University, often tells new recruits, “I can make you faster, but I can't make you fast.” In fact, even among the already fast, so-called trainability varies. Levels of intrinsic fitness and achieved fitness—or what you can attain through training—are evaluated based on traits such as muscle strength and cardiorespiratory fitness, itself normally measured by the volume of oxygen the body consumes in a minute. Both can differ dramatically from one person to the next. For instance, a young Olympian may have three times the maximum oxygen uptake as an elderly person in poor health—and twice that of an unfit person the athlete's same age.

For some, achieved levels of fitness are hard to shift, no matter how much drive they have—in which case, pushing too hard can lead to overtraining instead of improvement [see “The Overtraining Trap”]. When exercise scientist Nir Eynon of the Institute of Sport, Exercise and Active Living (ISEAL) at Victoria University in Australia and his colleagues subjected sedentary people to the same carefully controlled exercise programs, they found that some made almost no gains; at the same time, others increased their cardiorespiratory fitness by as much as 50 to 80 percent. “If you take two people—you and me—and we start at the same baseline and do exactly the same training and eat the same diet, we would both gain aerobic capacity, or muscle mass—or whatever—very differently,” Eynon says.

Elite athletes most likely are among a subset of people who reap the greatest benefits from training on top of high baseline levels of fitness. In 1998 geneticist Claude Bouchard of Pennington Biomedical Research Center of the Louisiana State University System and his colleagues found that both intrinsic and achieved levels of fitness tend to aggregate in families. When they tested 99 families, heritability explained about 50 percent of the variance in maximum oxygen uptake, for example. But Bouchard found no correlation between inborn fitness and trainability.

Of course, it all starts with the inborn gifts—as one 2014 study underscored. Evolutionary biologist Michael Lombardo of Grand Valley State University and his colleagues surveyed 15 male and female Olympic sprinting champions and the 20 fastest American men in U.S. history and found that, among those for whom biographical data were available, all were exceptionally fast before undergoing any formal training. Likewise, 64 collegiate championship-level sprinters and throwers in the same study all recalled being faster or stronger and better at throwing, respectively, than their peers as children. Of significance, the elite sprinters also showed big jumps in ability once they began formal training. “Strength, agility, speed and other athletic traits are all phenotypes that arise from interactions of the genotype with the environment,” Lombardo says. “To deny that there is any genetic variation in individuals that results in differences in athletic ability is really denying what we know about biology.”

That said, those underlying genetics have proved elusive. In 2016 Bouchard and his colleagues compared common alleles—or variants of a given gene—in 1,520 elite endurance athletes with 2,760 matched control subjects from four continents and came up completely empty-handed. “We thought we were in good shape to identify alleles, but it turns out that wasn't true at all,” he says; the team “failed miserably,” uncovering “not even one single allele reaching statistical significance.” The takeaway? Athletic ability probably arises from multiple gene variants, all with very small effect sizes. One such variant, though, may be ACTN3—a gene responsible for producing a protein used by fast-twitch muscle fibers, which contract quickly and provide bursts of power.

Athleticism and trainability are partially inherited, giving sisters such as Serena (left) and Venus (right) Williams an edge. CREDIT: GETTY IMAGES

In work that spanned more than a decade, geneticist Kathryn North of the University of Melbourne in Australia and her colleagues found that mice with ACTN3 have greater endurance. Eynon and his team at ISEAL are currently looking to prove the same link in humans. As he puts it, “We think you need this protein to sprint very fast.” About 16 percent of humans are naturally deficient. In contrast, among 300 world-class sprinters, Eynon and his colleagues found that deficiency approaches 0 percent, although it accounts for just 1 to 1.5 percent of the variance in total sprinting ability. “All that we can say with a very high level of certainty about this gene is that if you are deficient in it, you probably will not be an elite sprinter,” Eynon says.

Making It Happen

In addition to fitness levels, scientists have found telling mental traits that differentiate top athletes from amateurs. First, those competing at the national or international level appear to have more experiences of what is described as flow—a state of deep absorption in an activity during which performance seems to happen effortlessly and automatically. They are also more likely to feel something trainers call “making it happen”—involving intense focus and effort under pressure. Researchers suspect that athletes are not only better at channeling these mental states naturally but that they also sharpen them by having ample opportunity to experience them.

“There are certainly times athletes can win without experiencing flow or making it happen,” says sports psychology researcher Christian Swann of the University of Wollongong in Australia. “But when they do something excellent that they perceive as being close to their best performance, typically it will involve one of those states and sometimes both.” Swann and his colleagues are writing up new findings indicating that specific personality traits—including confidence, competitiveness, adaptive perfectionism (a form that relishes achievement while tolerating mistakes and avoiding self-criticism), optimism and mental toughness—seem to predispose individuals to achieving flow states.

Athletes also excel at certain perceptual and cognitive tasks. In 2013 Heloisa Alves, a cognitive neuroscientist then at the University of Illinois at Urbana-Champaign, and her colleagues recruited 87 elite Brazilian volleyball players and 67 matched controls to perform a number of tests of executive control, memory and visuospatial attention. Compared with nonathletes, the volleyball players demonstrated faster reaction times in two executive-control tasks and one visuospatial-attentional processing task, as well as greater mental control.

“Our basic understanding is that longtime physical training, specifically in sports, also involves some cognitive training, including attention and executive control,” Alves says. “So when you become an elite athlete, you somehow become an expert in certain cognitive abilities as well.”

The highest echelon of sportsmen and sportswomen may also have additional psychological differences, according to scientists who conducted studies for UK Sport, a governmental organization that promotes elite sports and athletic development. Specifically, UK Sport asked researchers to elucidate the fine-grained differences between elite athletes—professionals who compete at the Olympics or other major championships but who usually do not take home a major medal—and the so-called superelites who consistently win. UK Sport hoped to use its findings to foster more superelites and increase Britain's Olympic prowess.

Top competitors often enter a mental state called “making it happen,” involving intense focus under pressure. CREDIT: DEAN ALBERGA World Archery Federation via Getty Images

Sports psychologist Tim Woodman and his colleagues at Bangor University in Wales, collaborating with other universities and UK Sport, took up the effort, recruiting 32 male and female British athletes: 16 superelites who had won two to 18 medals each, including at least one gold, at major world championships, and 16 matched elites, who had never won a medal but had competed at the same level. The researchers interviewed the participants, their coaches and their parents, asking questions about the athletes' life histories. Because these interviews generated more than 8,400 pages of data, the researchers turned to a novel pattern-recognition program to identify differences among the groups.

What they found took them by surprise. “There's a long-standing view that happiness makes people achieve, but this study blows that assumption out of the water,” Woodman says. “Not only is happiness not the key, but it doesn't feature anywhere along the way.” Indeed, the team found that all of the superelites had experienced a critical negative event—their parents' divorce, a death, disease or some other perceived loss—early in life. And shortly after, all managed to discover sports, which they uniformly recalled as a highly positive turn, changing their course almost immediately. “Suddenly they felt valued, important and inspired, perhaps for the first time,” says Matthew Barlow, a postdoctoral researcher in sports psychology at Bangor who collaborated with Woodman.

Men and Women of Steel

Early trauma and recovery through sports were not all that Woodman and his colleagues found when they examined the life stories of superelite athletes. Very often these individuals had experienced another critical turning point later on in their sporting career. Whether this event was positive, like switching to an inspirational new coach, or negative, like the death of a loved one, it caused the athletes to redouble their efforts. “This big midcareer event reminds them of that original loss and motivates them at a deep-seated level,” Barlow theorizes.

This common narrative—from a loss to sports to deeper motivation—seems to shape the personality and outlook of superelites in predictable ways. For starters, Woodman says, “the importance of not losing is very keen.” Superelite athletes often express an obsessive need to win, as opposed to a desire for fame, happiness or money, which motivates many of their less successful competitors.

They are also “far more ruthless and selfish in their approach to their sport,” Woodman explains, not hesitating, for example, to split up with a spouse or partner if they think the relationship compromises their goals. And while less successful elite athletes tend to focus on beating opponents, the superelites put equal value on beating themselves and others. As Woodman says, “They always thought they could do better, no matter how well they performed.”

Woodman and his team have presented their findings at UK Sport's annual World Class Performance Conference and plan to publish all their results later this year. Overall, he says, their study implies that those who do not experience a traumatic event early in life “are less likely to have the drive necessary for that obsessive level of achievement.” No one is suggesting that coaches traumatize their protégés in hopes of unleashing a superelite, but there are some actionable lessons, Woodman notes. For example, talent scouts looking to develop Olympic athletes could keep an eye out for promising candidates “who had a rough ride somewhere along the way.”

Eynon stresses that no matter how far work progresses on the genetics and other determinants of elite performance, the findings should never be used to exclude people, with coaches selecting only those with the most biological promise. If that seems far-fetched, there are already a few companies selling direct-to-consumer genetic tests. These products purport to identify sprinting and aerobic ability from DNA in saliva samples, but, Eynon says, all are based on weak science. He also notes that not all serious athletes are elite, especially in team sports, so even if a test for elite potential did exist, it should not be used as a deterrent for playing sports.

“There are players who really shine,” Eynon says, “and ones who help. Don't you ever stop doing sports on the basis of a genetic test.” If nothing else, taking part in a sport that you love gives you a deeper appreciation of those athletes who are able to compete among the world's best.