By Paul Gardner
I left you last time with the vision of the virtually untrained high jumper Donald Thomas winning the world championship against Stefan Holm, who had spent the previous 25 years of his life training to perfect his jumping technique.
It is a story related by David Epstein in his wonderful book “The Sports Gene.” But Thomas is an exception. To become a world champion with so little work is rare. After the Thomas saga, Epstein takes us through the fascinating stories of why so many top sprinters come from Jamaica. And why the world’s leading distance runners come from East Africa, most of them from one tribe, the Kalenjin.
These are accounts that bring in the full mixture of genes and training and environment. Body build is important. Narrow hips and long legs make for good sprinters, something that links Jamaicans and American blacks -- because the ancestors of both were from West Africa, where the body type prevails. But there is something else to be considered. Malaria.
Malaria? Right. The theory involves a disorder known as sickle cell anemia for which there is a known gene. It is relatively common among American blacks and is generally not considered a good thing. It developed back in West Africa as a protective response to the malaria parasite, which attacks the hemoglobin in red blood cells. But in carriers of the sickle-cell gene, the red blood cells become sickle-shaped, and effectively cease to be of any use to the parasite as a source of hemoglobin.
If the subsequent loss of hemoglobin is high, it will cause anemia in the human. At lower levels it can be lived with, but then presents another problem: the lungs are now getting less oxygen. This is where the theory becomes controversial, when it claims that the problem of oxygen shortage was solved over the centuries, by a genetic switch in muscular makeup: from slow-twitch muscle fibers to fast-twitch muscles. Because fast twitch muscles use less oxygen. And it turns out that fast-twitch muscles are “essential for an elite sprinter.”
Sprinters have some 75% of the fast-twitch version, whereas most people have a more or less equal spread of fast and slow muscles, something that cannot be changed by training. Says Epstein: “No training study ever conducted has been able to produce a substantial switch of slow-twitch to fast-twitch fibers in humans.”
Genes then play a big role. In fact, there is single gene that appears to be much related to sprinting prowess. It has a name, ACTN3, and Epstein, as ever, will tell you all about it and its variant form, and its relationship to sprinters.
But another factor, environment, is important. In Jamaica, sprinting is a big deal. It matters, and youngsters showing promise are encouraged to stay with the sport -- where similarly gifted athletes in the USA would get switched to basketball or football. Usain Bolt wanted to be a soccer player. His second choice was cricket. But once his running talent was suspected, coaches made sure he stayed with track.
From West Africa, Epstein takes us over to East Africa, the powerhouse area for long-distance runners. Mostly from the Kalenjin tribe, living in Kenya and Ethiopia. Do they have a genetic advantage from body build? Possibly -- they are among those classified as Nilotic -- slender bodies, narrow hips, long legs.
A Danish study compared a group of Kalenjin youngsters with a similar group of Danish boys and found almost nothing to support theories that the Kalenjins had a high proportion of slow-twitch muscle fibers in their legs, that they had a superior aerobic capacity (the amount of oxygen used in strenuous exercise), or that they responded better to endurance training.
As expected, the Kalenjin had slightly longer legs, which was where a big difference emerged: not so much the length of the Kalenjin legs, but the thickness of the lower legs, which was some 15% to 17% less in the Kalenjins. The finding is considered key, for extra weight in the lower legs has a big effect on running economy (again, a measure of oxygen consumption). “We have solved the main problem” of the Kenyan super-runners, claimed one of the researchers, who might have thought a bit more about his use of the word “problem.”
A genetic advantage then, in body build, those slender ankles, those long, almost spindly legs.
But nurture plays a big role here. There’s the altitude. All the runners live in the Rift Valley -- at a height of between 6,000 to 9,000 feet. Just right. A height where the body responds by upping its output of red blood cells. And if you’re born there and grow up there, you tend to develop larger lungs.
Even the 10,000-hour mentality can get a word in here. Epstein tells of the young kids -- most of them, it seems -- who regularly runto and from school, often over distances of several miles. That must be wonderful training. But not, apparently, necessary training. Epstein, never shirking awkward facts (and the field of genetics bristles with them), blandly mentions two Kenyans: Paul Tergat “the greatest cross-country runner in history” (“My school was very close. I could walk to school.”); and Wilson Kipketer “one of the greatest middle-distance runners of all time” whose school was next door to his home.
Intertwined (you can read that as entangled) with all that is the question of response. Obviously, training helps -- but to what extent? Studies have been done (that’s yet another surprise in Epstein’s book -- the sheer volume of research that has been done on the many aspects of athletic performance).
So we learn about responders, and the now famous HERITAGE study. At four different sites, fit but previously untrained volunteers were put through a regular exercise program. From all four sites came remarkably similar results for the effects of the program on aerobic capacity: 15% showed little or no improvement, while another 15% showed dramatic improvement (up to 50%) with the remainder of the volunteers somewhere between the two extremes.
By 2011 the HERITAGE researchers reported that they had pinned down 21 gene variants from which they could predict aerobic response to exercise. Exercise certainly did work -- but it worked best when the exerciser already had the genes making him a high responder.
An ideal recipe suggested itself for running success: an athlete with a naturally high aerobic capacity who was also a high responder. In Kansas, some 30 years before the HERITAGE research, that magic combination had been found, almost serendipitously, in a high school athlete named Jim Ryun, who went on to twice break the world one-mile record.
Just as there appears to be a genetic basis to the response to training, it seems that genes may also be involved in what is called will-power. The evidence for this comes from dogs -- Alaskan huskies bred to win the famous 1,000-mile Iditarod race for dogsleds. Bred certainly not for speed, and not so much for endurance, as for persistence. Dogs that were always pulling, always wanted to pull. Even after a race was over. A trait that was evidently genetic, because the dogs that have this tremendous will-power can be bred.
Dogs can be bred, just as thoroughbred race horses are. Humans are not bred that way. Not yet, anyway (though Epstein gives us the lowdown on the giant Chinese basketball player, the 7-foot-5 Yao Ming, who was conceived as a result of a union between extra-tall parents engineered by the Chinese basketball federation).
In the absence of athlete breeding programs, and given the uncertainty and complexity that envelops so much of the gene world, is all this new knowledge of any practical use? Is genetic testing, for instance, of any value.
Yes, says Epstein ... because it can save lives. It can detect the genetic disorder known as HCM -- hypertrophic cardiomyopathy -- a leading cause of sudden natural death in young people. For people with the HCM gene, exercise can be dangerous, even fatal.
The NCAA already screens football players for the sickle-cell gene; it adopted that measure after a series of sudden deaths involving black players during training were linked to the disease.
Commercial interests have scented profits, of course. Genetic profiling is now on offer. Whether it is reliable is questionable. Just this past week the FDA shut down a company that, for $99.00, was offering profiles (to show how personal genetic codes may affect future health). The FDA said the company had failed to supply any of the required proof that its tests were accurate.
On the sports side, most interest, so far, has centered around ACTN3, the sprinting gene. For a fee, parents can establish whether their kids (quite possibly still in diapers) have the right versions of the gene and may be therefore potential gold-medal winners. The knowledge seems to be of little value. Absence of the correct genes considerably reduces but doesn’t rule out success. But their presence is no guarantee of success.
In fact, there are few, if any, tidy answers to the growing number of questions. Which makes it all the remarkable that Epstein has been able to come up with such a riveting book. No one is going to be satisfied -- not the 10,000-hour people, nor the determined gene-theorists, nor those who see racial superiority or inferiority in athletics, nor the feminists and particularly not those looking for a straightforward road map to better performances.
Epstein talks more than once about the complexity of genetics. Noting that, in the heady days following the sequencing of the human genome in 2000, scientists were carried away and “underestimated the complexity of genetics.”
Maybe that’s still the case. As more is learned, the more complex things get. And therein lies the fascination.
Next time: Genes and Sport, Part 3. What Soccer Can Learn from Genetics.
Genes and Sport, Part 1: Complexity, Nature vs. Nurture, and the Holes in the 10,000-hour Theory
The Sports Gene. Inside the Science of Extraordinary Athletic Performance. By David Epstein. Current, 2013. $26.95.