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Genes affect body weight. The GIANT (Genetic Investigation of ANthropometric Traits) Consortium study of 100,000 adults found six DNA variants that influence heft. The FTO gene, in itself, accounts for several pounds in studies, possibly by influencing one’s taste for fatty foods. But, as anyone who has ever gorged himself on Thanksgiving dinner and then hopped on a scale can attest, weight is substantially affected by lifestyle.
Fat is the tissue in the body that is most responsive to training and diet. (And weight is extremely responsive to certain drugs. When Norton and Olds examined the inflating size of NFL defensive tackles, they found an eye-catching acceleration in size in the late 1960s and early ’70s, when steroids began to proliferate in football. From the 1940s to the 1990s, the body mass index of an NFL defensive tackle rose from 30 to 36. For a 6'2" tackle, that’s a rise in weight from 234 pounds to 280 pounds.)
Clearly, the FTO gene has been around since long before the recent obesity epidemic in the industrialized world. More genes that influence weight are sure to be found—studies of twins and adopted children suggest there are more out there—and the complex interplay of genetics, lifestyle, and weight are only beginning to be illuminated. Even combined, all of the DNA variants that the GIANT Consortium identified accounted for only a small fraction of bulk. (Based on my DNA analysis, I am entitled to attribute just 8.5 of my 150 pounds to those genes.)
And just as an individual’s proportion of fast- and slow-twitch muscle fibers influences his muscle growth potential, it also influences his fat-burning capacity. Researchers in the United States and Finland have independently shown that, while adults with a high proportion of fast-twitch fibers can pack on muscle, they have a more difficult time losing fat. Fat is primarily burned as part of the energy-making process that occurs in slow-twitch muscle fibers. The fewer slow-twitch muscle fibers an individual has, the lower his capacity to burn fat—one possible reason that sprint and power athletes tend to be stockier than endurance athletes, even before and after their competitive years.
And while it is obvious that diet and training can dramatically alter an athlete’s build, there are limits. Limits delineated by an individual’s skeleton.
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Francis Holway, an exercise and nutrition researcher in Buenos Aires, has been obsessed with the limits of body types since childhood. His first inspiration was the story of Tarzan. He was fascinated by how the son of a British lord adopted by apes and transplanted to a jungle environment could develop the rhino-wrestling physique and vine-swinging skills to thrive. Holway’s first experiments, at the age of seven, came when he would gulp down spoonfuls of oatmeal and then flex his biceps right after the meal to see if they had grown.
As a kid, he first thought that the sport shaped the body; that basketball players would grow tall from playing and weight lifters would become squat from squatting. To some degree, the research he has conducted as an adult has borne out similarly startling phenomena. Holway measured the forearms of a group of tennis players ranked in the top twenty in the world and found that their racket arms grew slightly differently from their nonracket arms. The racket-side forearm bones of the players grew around a quarter-inch longer than the forearm bone of the nonracket arm. And the elbow joint widened a centimeter. Like muscle, bone responds to exercise. Even nonathletes tend to have more bone in the arm they write with simply because they use it more, so the bone becomes stronger and capable of supporting more muscle. “It’s just amazing how the bones can adapt to repeated stress,” Holway says. Those tennis pros literally served and volleyed their ways to longer forearms. And yet, this malleability is limited.
Libby Cowgill, an anthropologist at the University of Missouri, has studied skeletons from around the world in an effort to determine whether certain populations have built strong skeletons through childhood activity or whether they are simply born with robust skeletal scaffoldings capable of supporting mounds of muscle. “We can see differences in the strength of bones in different populations already at one year of age,” Cowgill says. “What I’ve found indicates that these differences are just there. They are exacerbated over the course of growth based on what you’re doing, but it looks like people are born with genetic propensities to be strong or to be weak.”
In one study, she compared the skeletons of Mistihalj people—a group of medieval Yugoslavian herders—to the skeletons of kids from 1950s Denver. “The herders’ kids are the biggest, buffest kids I’ve ever seen,” she says. “Based on data of modern American children, we’re just puny in terms of the amount of bone we have.” But might a strict childhood training program be able to transform any American tot into a mighty medieval herder? “There’s a lot you can do with activity, and especially starting it earlier,” Cowgill says. “But it’s looking more and more like there’s a genetic component as well.”
The skeleton you are bequeathed has a lot to do with whether you will ever be able to make the weight required for a particular sport. Holway compares the skeleton to an empty bookcase. One bookcase that is four inches wider than another will weigh only slightly more. But fill both cases with books and suddenly the little bit of extra width on the broader bookcase translates to a considerable amount of weight. Such is the case with the human skeleton. In measurements of thousands of elite athletes from soccer to weight lifting, wrestling, boxing, judo, rugby, and more, Holway has found that each kilogram (2.2 pounds) of bone supports a maximum of five kilograms (11 pounds) of muscle. Five-to-one, then, is a general limit of the human muscle bookcase.*
“We’ve had people come in for consultation and they want to increase their muscle mass for aesthetic reasons,” Holway says. “We measure them, and if they’re close to five-to-one we ask them how long they’ve been at this same level of development or strength. They’ll say for the last five years or seven years, and they haven’t been able to surpass it.” Holway experimented on himself, spending years in heavy weight training with a diet high in protein and supplemented by creatine. But as he closed in on five-to-one, inhaling more steaks and shakes only added fat, not muscle.
Male Olympic strength athletes whom Holway has measured, like discus throwers and shot putters, have skeletons that are only about 6.5 pounds heavier than those of average men, but that translates to more than 30 pounds of extra muscle that they can carry with the proper training. Holway uses his measurements to help tailor athletes’ training. In the shot put, for example, an athlete needn’t move himself very far, so even adding extra fat might be worthwhile, since the athlete needs to pack on bulk to become relatively more massive than the object being thrown. But in javelin, where the athlete needs to both run fast and throw hard, he should be wary of trying to add weight beyond the five-to-one ratio, as it will likely be fat. Or consider a Sumo wrestler, or an offensive lineman in football who simply wants to be difficult for his opponent to move. He might do well to add extra fat. Offensive linemen are incredibly strong, but they most certainly are not ripped.
Again, when innate biological differences are taken into account, it becomes clear that successful training plans are those tailored to the individual’s physiology. As Dr. J. M. Tanner, an eminent growth expert (and world-class hurdler), wrote in Fetus into Man: “Everyone has a different genotype. Therefore, for optimal development, everyone should have a different environment.”
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Heaving sports performance to untouched heights requires both specialized training and specialized bodies to be trained.
Today, the expanding universe of athletic body types is slowing down. Much of the self-sorting, or artificial selection, is finished. The tall athletes are no longer getting taller compared with the rest of humanity at the rate they were two decades ago, nor the small smaller. And the march of constantly shattered world records is slowing right along with it.
Over most of the twentieth century, the adage “records were made to be broken” rang chronically true.
But athletic records in most, but certainly not all, events that have high historical participation are now inching forward—if, that is, they are moving forward at all. The coveted world records in the men’s mile and 1,500-meters (the race close to the mile that is run outside the United States) were broken collectively about eight times per decade from the 1950s to 2000, but not at all since. Other records have continued to creep down, but usually by small margins. It will be intriguing to see whether the financial success of Usain Bolt, who dropped records by rather large margins, draws more athletes with his unusual combination of explosiveness and height away from other sports to sprinting.
“There are still some unexploited parts of the world, but we’ve reached much of the global market,” says Tim Olds, one of the Big Bang of body types scientists. “We’re getting closer to reaching the limit of our source populations for bodies. Population progression is slowing globally, so we’re going to see slowing growth in both body size and body shapes, and in records as well.” Just as exploring the earth must once have seemed like an endless endeavor for adventurers, perhaps the era of constant record shattering is largely in the past, and the future will be one of baby steps forward.
As the expanding universe of sports physiques has sped outward, finding those increasingly rare bodies has fostered an increasingly extensive, and expensive, global talent search.
In that endeavor, no league has been more successful than the National Basketball Association.
8
The Vitruvian NBA Player
Long before he became a pop-culture trope, before he dated Madonna or married Carmen Electra, or married himself as a publicity stunt; before he posed for the cover of Sports Illustrated with fire-engine-red hair, wearing a metal-studded choker and a smug look and holding a blue parrot; before he announced he would start a topless women’s basketball league, and way before he hung out with North Korean leader Kim Jong-un, Dennis Rodman was just an insecure little boy.
Every night before he fell asleep as a child in the Oak Cliff housing projects in Dallas, he would lie awake and think: “There’s something big out there waiting for Dennis Rodman.” Little did he know at the time, the something big would be himself.
Back then, Rodman’s sisters were the basketball stars. Both would become college All-Americans, while Dennis, the family runt, was short and awkward and struggled to sink a layup. He warmed the bench for a half season of high school basketball and then quit. He was 5'9" when he graduated, and endured taunting by his friends when he tagged along with his bigger, younger, more athletic sisters.
After graduation, Rodman took a job on the graveyard shift sweeping floors at the Dallas/Fort Worth International Airport. One night, he stuck a broom through the safety gate of a shuttered airport gift shop and fished out a few dozen watches that he distributed among his friends. He got caught. Rodman didn’t last long in that job. But his something big had already started to happen. In the two years since high school, Rodman had grown like kelp. He was working part-time scrubbing cars at an Oldsmobile dealership for $3.50 an hour when he topped out at 6'8".
So Rodman started to play basketball and found that he was suddenly less gawky despite being taller and more muscular. He caught on to the game so quickly it was as if the basketball fairy had left hoop skills under his pillow one night. In his words: “It was like I had a new body that knew how to do all this shit the old one didn’t.”
A family friend convinced Rodman to try out for a local community college team. He played for a while, but dropped out with academic problems. The following year, 1983, he took a basketball scholarship to Southeastern Oklahoma State, a little-known NAIA school. He dominated there for three years, averaging 25.7 points and an otherworldly 15.7 rebounds per game. The rest is hardwood history. Rodman was drafted into the NBA and in fourteen years won five championships, was twice named Defensive Player of the Year, and became the greatest rebounder in NBA history. In 2011, the man who played hardly any organized basketball before he was twenty-one was inducted into the Basketball Hall of Fame.
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Only marginally less inevitable than death and taxes during the 1990s was the Chicago Bulls winning the NBA championship.
Dynastic dominance came on the backs of three future Hall of Famers, and three nick-of-time growth spurts. Before the triune pillars of the Bulls dynasty had their height, their skills alone did not elevate them above the crowd.
There was Rodman, of course. Then there was Scottie Pippen, who had a similar story. He was 6'1" when he graduated from high school and started out as the team manager at the University of Central Arkansas. He sprouted to 6'3" by the end of his first year and started playing for the team. By the end of the following summer, Pippen was 6'5". By his junior season, Pippen was 6'7" and NBA scouts began to swarm the stands to watch unheralded Central Arkansas. Years later, he was selected as one of the fifty greatest players in NBA history and was inducted into the Hall of Fame one year before Rodman.
Michael Jordan didn’t cut it quite so close. Jordan was already a good basketball player in high school—he started dunking as a 5'8" freshman—but he comes from a comparatively diminutive family and was already anomalous at six feet as a high school sophomore. As a high school junior, Jordan was being evaluated by college scouts, but looked like a better fit for a small school. By Jordan’s own reckoning, his 5'7" brother Larry was as athletic as he and held the upper hand in their backyard games, until Michael’s kelp phase. He grew six inches late in high school and dropped baseball to focus on basketball. He earned a scholarship to powerhouse North Carolina. The rest of the story hardly needs telling.
Rodman, Pippen, and Jordan formed the nucleus of a Bulls team that went 72-10 in the 1995–96 season, a feat unequaled before or since, and their biographies are testaments to the primacy of height.
That isn’t to suggest that being 6'6" or 6'8" automatically makes a professional basketball player, much less a Hall of Famer. As ESPN personality Colin Cowherd said on his radio show, “Talent doesn’t fall out of the womb . . . there are a million guys in America who are six-foot-eight who aren’t in the NBA.” But then, that’s not right either.
Based on data from the United States Census Bureau and the National Center for Health Statistics, there are likely fewer than twenty thousand American men between the ages of twenty and forty who are at least 6'8". So a Dennis Rodman or a LeBron James is not one in a million—compared to men of equal height—but rather one in a pool the size of Rolla, Missouri.
Height is an incredibly narrowly constrained trait among humans. Fully 68 percent of American men are in just the six-inch range from 5'7" to 6'1". The bell curve of adult height is a Himalayan slope that falls off precipitously on either side of the mean. A mere 5 percent of American men are 6'3" or taller, while the average height of an NBA player perennially hovers around 6'7". Suffice it to say that there is startlingly little overlap—far less than Cowherd suggested—between the heights of humanity and those of NBA players.
While inhabitants of the industrialized world grew taller over much of the twentieth century at a rate of about one centimeter per decade—at least partly because of increased protein intake and the decline of growth-stunting childhood infections, and perhaps because people are mixing genes more widely, with “tall” genes dominating “short” genes—NBA players have been growing at more than four times that rate, and the tallest of the tall NBA players at ten times that rate.
In Outliers, Malcolm Gladwell makes a point about height in basketball by comparing it to IQ. There is a threshold, he writes, above which more does not really matter. Above an IQ of 120—which already eliminates most of humanity—he argues, one is already smart enough to consider the most difficult intellectual problems, and more IQ does not translate into real-world success. In basketball, he adds, “it’s probably better to be six two than six one . . . But past a certain point, height stops mattering so much.” But the �
��threshold hypothesis” of IQ is not supported by the work of scientists who specialize in that field, nor is the threshold hypothesis of NBA height supported by player data.
Based on data from the NBA and NBA predraft combines (using only true, shoes-off measurements of players), the Census Bureau, and the Centers for Disease Control’s National Center for Health Statistics, there is such a premium on extra height in the NBA that the probability of an American man between the ages of twenty and forty being a current NBA player rises nearly a full order of magnitude with every two-inch increase in height starting at six feet. For a man between six feet and 6'2", the chance of his currently being in the NBA is five in a million. At 6'2" to 6'4", that increases to twenty in a million. For a man between 6'10" and seven feet tall, it rises to thirty-two thousand in a million, or 3.2 percent. An American man who is seven feet tall is such a rarity that the CDC does not even list a height percentile at that stature. But the NBA measurements combined with the curve formed by the CDC’s data suggest that of American men ages twenty to forty who stand seven feet tall, a startling 17 percent of them are in the NBA right now.* Find six honest seven-footers, and one will be in the NBA.
Kevin Norton and Timothy Olds, the Big Bang of body types scientists, charted the increase of seven-foot players in the NBA from 1946 to 1998 and found that the proportion of seven-foot NBA players rose slowly but steadily for thirty-five years, from zero in 1946 to about 5 percent of all players in the early 1980s, just before the winner-take-all basketball market kicked into hyperspeed.
The Sports Gene: Inside the Science of Extraordinary Athletic Performance Page 14