The Story Behind the Amazing Success of Black Athletes, by Jon Entine

Shattering Racist Myths: The Science Behind Why Kenyans Dominate Distance Running

Even a casual mention that meaningful genetic differences exist between populations can ignite a firestorm and threaten a career. Ask Jimmy "the Greek" Snyder. Or Roger Bannister, the first man to break the four-minute barrier in the mile, in 1954. In a speech before the British Association for the Advancement of Science in 1995, Sir Roger Bannister, the distinguished neurologist and retired Oxford dean was showered with ridicule for venturing his opinion "as a scientist rather than a sociologist" that all athletes are not created equal. "I am prepared to risk political incorrectness," he said, "by drawing attention to the seemingly obvious but under stressed fact that black sprinters and black athletes in general all seem to have certain natural anatomical advantages."

That's the explosive "N" word - natural. Because of the pseudo-science that has historically plagued research into human differences, assertions that biology predetermines or even significantly influences human behavior runs into a wall of political incorrectness. That's the politics.

While everyone readily accepts that evolution has turned out blacks with a genetic proclivity to contract sickle cell and Jews of European heritage who are 100 times more likely than other populations to be afflicted with the degenerative mental disease Tay-Sachs, it is widely perceived as racist to suggest that blacks of West African ancestry have evolved into the world's best sprinters, Asians among the best divers, East Africans the premier distance runners, and whites the top weightlifters.

Yet the science is quite clear and the empirical evidence consistent and overwhelming. A look at the ancestry (or home country) of runners holding the top 100 times in eight distances, from the 100 meters to the marathon, makes it clear that African domination is deep as well as broad:

  • Blacks who trace their ancestry to West Africa, including African Americans, hold more than 95 percent of the top times in sprinting;
  • Whites are virtually absent from the top ranks of sprinting; though whites have traditionally done well in the longer endurance races, particularly the marathon, their ranks have thinned in recent years;
  • Athletes from one country, Kenya, make up more than one-third of top times in middle and long distance races; including top performances by other East Africans (most from Ethiopia), that domination swells to almost 50 percent.
  • North Africans do well at middle distances;
  • Mexicans (Native Americans), are strongest at the longest races, 10,000 meters and the marathon;
  • East Asians are competitive only at the event requiring the most endurance, the marathon, and at ultra-marathons.

Why do athletes of African ancestry dominate running? Whereas the West African population evolved in the lowlands, East Africans (who are relatively slow sprinters but the world's best distance runners) trace their ancestry to mountainous terrain. Kenya, with 28 million people, is the powerhouse. It is a genetic stew, with studies indicating a mixture of genes from invading Arabs and Middle Easterners. One tiny district, the Nandi, with only 500,000 people, sweeps an unfathomable 20 percent of major international distance events, marking it as the greatest concentration of raw athletic talent in the history of sports.

At the Seoul Olympics in 1988, Kenya shocked the running world when it's top male runners won the 800m, 1500m and 5,000 meters, plus the 3,000-meter steeplechase. Based on population percentages alone, the likelihood of such a performance is one in 1.6 billion. The Kalenjins of the Great Rift Valley adjacent to Lake Victoria, a tribe of half a million people, win 40 percent of top international distance running honors - and three times as many distance medals as athletes from any other nation in the world.

This East African domination (and by some Moroccans and Algerians who are much closer, genetically, to East than West Africans) has been slow to emerge. Ethiopia's Abebe Bikila shocked the world at the 1960 Rome Olympics when, running barefoot, he won the marathon. But most East Africans did not have the money or means to compete. By the1980s Africans began trickling into long distance running, although soccer, at which Kenyans (and East Africans generally) fair poorly, was and is the national sport.


Over the years there have been more than two hundred studies comparing the body composition of athletes, with the work of British physician James M. Tanner the most famous. His The Physique of the Olympic Athlete, published in 1960 after the Rome Olympics, found an ideal body for each sport, although the study noted considerable overlap in types - a classic bell curve. Sprinters were the most muscular. Beginning at 400 meters on up to the marathon, athletes competing in these events were progressively less muscular in the upper body. Long-distance runners were generally small, short-legged, narrow-shouldered, and ectomorphic, or lacking in muscle.

"Amongst competitors in both track and field events there are large significant racial differences," Tanner wrote. As nature would have it, different populations are better suited to excel at anaerobic activities such as sprinting, jumping, and lifting, than at aerobic sports such as distance running, cycling, and swimming.

We see these differences on the playing field, but they are apparent at the micro level as well. In the mitochondria of cells, the body's powerhouse, oxygen combines with the glucose released by carbohydrates and, eventually, fats to produce sustained energy. When the body demands quick bursts, it breaks down carbohydrates quickly, if incompletely. At roughly 400 meters, about 40-50 seconds of running for a top athlete, or 100 meters in swimming, the body has depleted much of its anaerobic capacity. That is the point at which anaerobic athletes experience an accumulation of lactic acid, the waste product of the muscles. If physical activity continues past this bio-physiological divide, the body begins to process energy more deliberately. Scientists are definitive in their findings that athletes of West African ancestry are the most anaerobically efficient athletes, East African are the fittest aerobically, and whites fall in the middle.

For years it was axiomatic that muscles have two types of fibers - white, or fast-twitch, which were thought to be adapted for power movements, such as leaping or sprinting; and red, or slow-twitch, which were adapted for endurance. Now we know the model is more complicated. There are in fact two different types of fast-twitch fibers, one more metabolically efficient. Whites on average have a higher percentage of slow-twitch fibers than West African blacks who generally have more of both types of fast-twitch fibers.

Geneticist and exercise physiologist Claude Bouchard at Laval University in Quebec City, has run numerous experiments comparing two populations, French-Canadian and West African students. Using long needles inserted into the thighs of test subjects, Bouchard's team extracted tiny sections of fibers, which look to the naked eye like pieces of raw meat. They were chemically treated to reveal metabolic differences, put on a glass slide, and slipped under a high-power microscope, where they appeared as a collage of tiny red and white crocodile scales. The West Africans, by a ratio of approximately two to one, had more of the larger fast-twitch fibers. The researchers concluded that the force generating capacity of type-II muscle fibers at high velocity, the speed and tempo of movements, and the capacity of an individual to adapt to exercise training are all genetically influenced.

Although physical activity can improve fitness, it generally cannot alter a person's biological endowment by converting fast-twitch fibers to slow-twitch ones, or vice versa (although people do gradually and permanently lose fast-twitch muscles as a result of aging). It's estimated that 40 percent is due to environmental influences such as exercise, whereas 45 percent is associated with genetic factors (the remaining 15 percent is due to sampling error). At the far end of the performance bell curve in sprinting, where small differences can be crucial, genetics clearly circumscribes possibility.


Although fiber composition can significantly affect performance, it is not sufficient by itself to ensure high performance. Since endurance is only about 25 percent inherited, training plays an integral role-but more so in blacks than whites. Experiments show that with only a modest amount of training, blacks can experience an explosive rise in exercise capacity, while even with far more effort whites don't improve nearly as much. In contrast, it appears that no amount of training can break through genetically-imposed, inherited limits on anaerobic capacity-the ability to sprint and jump. Thus, although fiber type alone does not itself guarantee a champion, if an athlete does not have a certain proportion of fast-twitch muscles, he or she can't hope to be a champion sprinter or jumper. In practical terms, this detail suggests that sprinters are born, not made.

If genetics and race really do matter in athletic performance, then we might expect to find noticeable differences in the ways different population groups sustain anaerobic and aerobic functioning. Sure enough, by applying population genetics to athletic performance and examining the aerobic/anaerobic energy cycle, scientists are beginning to understand the racial pattern in sports.

Timothy Noakes, long-time director of the Sport Science Center at the University of Cape Town Medical School, and author of many scholarly books, including Lore of Running, has observed that black South Africans, who share much of their genetic ancestry with East Africans, sweep more than 90 percent of the top places in endurance races held in his country, despite the fact that blacks represent no more than one-quarter of the active running population. Noakes has attempted to figure out why in his laboratory. In a treadmill study, black marathoners consistently bested whites. Although white runners matched or exceeded the black runners at distances up to 5,000 meters, blacks were "clearly superior at distances greater than 5km." The fine print in the data was particularly revealing. There was a dramatic difference in the ability of the blacks to run at a higher maximum oxygen capacity. In the case of the marathoners, blacks performed at 89 percent of the maximum oxygen capacity, while whites lagged by nearly 10 percent. The muscles of the black athletes also showed far fewer signs of fatigue as measured by lactic acid.

Noakes noted a link between his findings and the training habits of well-known Kenyan runners who report favoring low-mileage, high-intensity workouts. This presented a nurture/nature conundrum: Does hard training lead to a change in oxidative capacity and fatigue resistance, or does it merely reflect a genetically well-endowed athletic machine?

The answer can be found in the wild card in performance: muscle efficiency. David Costill, former head of the Human Performance Laboratory at Ball State in Muncie, Indiana, has shown that the adaptability of the muscle fiber for aerobic metabolism - its oxidative potential - is more important than the basic composition of the muscle. More aerobically efficient fibers produce fewer fatigue-producing lactate toxins, resulting in better performance. And although fiber composition is genetically fixed, which effectively limits the pool of possible successful athletes in each event, exercise can help muscles better utilize oxygen.

A team from South Africa and Australia, including Noakes, has found an apparent link between oxidative capacity, resistance to fatigue, and race. The researchers measured "running economy"-the amount of metabolic work (and therefore oxygen consumption) that is required to run at a given speed, much like the fuel economy of a car. Running economy can be affected by a variety of factors both environmental, such as running technique, and physiological, such as body-mass distribution and muscle elasticity. "We've shown that the oxidative enzyme capacity of the [black] athletes we looked at was one and a half times higher on average than the white runners," reported Kathy Myburgh, a co-author of the report and senior lecturer at the University of Stellenbosch in South Africa. Comparing black and white athletes with nearly identical race times, the researchers found that blacks were both more efficient runners and able to utilize a considerably higher percentage of their maximum oxygen potential - a decided advantage if two athletes otherwise have the same capacity.

"Whilst the current study does not elucidate the origins of these differences," the report concluded, "the findings may partially explain the success of African runners at the elite level." A subsequent study determined that the superior fatigue resistance during high-intensity endurance exercise is partially related to the higher skeletal-muscle oxidative capacity and lower plasma lactate accumulation found more commonly in blacks.


Noakes's colleague, Bengt Saltin, head of the Muscle Research Institute in Denmark, has come to the conclusion that certain population groups, including Northern Europeans, who are notable endurance runners and cross-country skiers, may have superior fatigue resistance encoded in their genes. He has found that Scandinavian distance runners, Kenyans, and South African blacks all have consistently lower blood-lactate levels and perform more efficiently than athletes from other regions, the likely result of their having evolved in mountainous regions. Population genetics - ancestry - is the key determinant.

Saltin brought a half-dozen established Swedish national class runners to St. Patrick's High in Iten, Kenya, in 1990 to see how they might match up against up-and-coming East African schoolboys. It was a demoralizing experience for the Swedes. National champion after national champion was soundly trounced in races from 800 meters to 10 kilometers. Stunned, Saltin estimated that in this one tiny area of the Rift Valley there were at least five hundred school boys who could best his national champions at 2,000 meters.

In a subsequent study Saltin brought several groups of Kenyans to the Karolinska labs in Sweden, where he was then working. Muscle-fiber distribution was similar for the Kenyans and Swedes. But biopsies of the quadricep muscles in the thighs indicated that the Kenyans had more blood-carrying capillaries surrounding the muscle fibers and more mitochondria within the fibers. That's important because mitochondria act a little like power stations, processing the glucose with oxygen brought in by breathing into energy. The Kenyans also were found to have relatively smaller muscle fibers than the Swedes, which Saltin speculated might serve to bring the mitochondria closer to the surrounding capillaries. This process aids in oxidation, bringing more "fuel" to the mitochondria, the engine of the muscles.

The Kenyans also showed little ammonia accumulation in their muscles from protein combustion, and less lactic-acid buildup. They have more of the muscle enzymes that burn fat, and their glycogen reserves are not burned as quickly, which improves endurance. Most impressively, they are able to take months off from regular training and then regain their old form quickly. When they do train, more than half of their total mileage occurs at heart rates of 90 percent of maximum, far higher than the rate for Europeans or Americans. In general, Saltin reported a 5 to 15 percent greater running economy at far less mileage, but at a higher intensity. Saltin has privately suggested that Kenyans appear to be innately efficient, durable, and fast - with the most perfect aerobic potential measured so far on earth.

Although there is no one genetically consistent African population, the environment appears to have resulted in some characteristics shared across populations. Bouchard is persuaded that a large fraction of both West and East African blacks enjoy biological advantages for power or sprint events and endurance activities, respectively. "West Africans have more of the key anaerobic enzymes in their skeletal muscle, those enzymes being responsible for regenerating the energy in the muscle cell through anaerobic pathways," wrote Bouchard. We are talking here about a two-fold difference between a significant fraction of blacks from West Africa and whites from North America. East Africans, on the other hand, seem to have more ability to mobilize the energy stored in adipose tissue in other body depots and to use that energy for prolonged periods of exercise. The key point is that these biological characteristics are not unique to either West or East African blacks. These characteristics are seen in all populations, including whites. However, based on the limited number of studies available, there seems to be more African Blacks with such characteristics than there are in other populations.

Considering the hotter-than-hot nature of the debate, it is not surprising that the most balanced views originate with those outside the United States. "There is an environment in the US which prevents individuals from even talking about this topic," said Bouchard. "I do not feel this pressure at all here in Canada. We talk openly about this issue and treat it as a scientific matter. I believe that we need to look at the causes of differences in performance between races as legitimately as we do when we study or discuss differences in diseases between the various races. I have always worked with the hypothesis that ignorance fosters prejudice. [Critical inquiry] is the greatest safeguard against prejudice."

Measured by fractions of a second, or wins and losses, sport comes as close as we can get to an objective, racially neutral scoring system. "I've been asked many times how an academic can waste time studying the differences between black and white people," said exercise physiologist Kathy Myburgh. "I said, 'Well, if you're a scientist and you're studying obesity, who do you compare obese people with? You compare them with thin people. But if you are a physiologist and you want to compare your best runners with those not quite as good, you compare the black ones with the white ones, because the blacks clearly are performing better.'"

Arthur Ashe, Jr., the first black man to win the US Open, Australian Open, and Wimbledon singles tennis titles, wrestled with this controversy while writing his groundbreaking A Hard Road to Glory, which catalogues the history of black accomplishment in sports. He accumulated thousands of anecdotes of how cultural and environmental forces had shaped black success in sports. Still, Ashe could not put the genetic issue to rest. When asked about what he had come to believe after years of research, whether blacks had a physical advantage, Ashe responded deliberately: "The results are outstanding, nothing short of stellar.

"Damn it," he sighed, frustrated at the political incorrectness of his own beliefs. "My heart says 'no,' but my head says 'yes.' Sociology can't explain it. I want to hear from the scientists. Until I see some numbers [to the contrary], I have to believe that we blacks have something that gives us an edge."

Ashe of course is only recognizing what we all intuitively know unequivocally: Population genetics and ancestry matter, a lot. Yet it should never be forgotten that genes are not the ultimate factors in elite performance. While genetics will determine if you have a chance to be an elite athlete, intelligence, dedication, and serendipity are the final arbiters of who wins and loses.

"It's the brain, not the heart or lungs, that is the critical organ," Roger Bannister told me. "But one would have to be blind not so see a pattern here. I hope we are not at a time and place where we are afraid to talk about remarkable events. I hope not."

Back to Part I

Jon Entine is the author of "Taboo: Why Black Athletes Dominate Sports and Why We Are Afraid to Talk About It."

© 2000 by Jon Entine. All rights reserved. Reprinted by permission. For more of Entine's work and reviews, visit his site at