Champaign, IL—Runners, coaches, and exercise scientists often wonder whether running performances are determined primarily by genetic factors or by the environment. If performances are indeed primarily shaped by genes, coaches and serious runners will begin using cheek swabs to learn what their DNA dictates about their running futures, and gene doping could play a prominent role in elite competitions. But according to Owen Anderson, author of the forthcoming Running Science (Human Kinetics, 2013), both genetics and environment play a vital role in determining running performance.
According to Anderson, East African dominance of distance running is often cited as evidence that genes are the strongest determinants of endurance performance: African male runners captured 8 of the 12 gold medals in the 1500-meter, 5K, and marathon competitions in the 2012 Olympic Games. “Such African dominance was not present as recently as 20 years ago, when European runners ruled supreme at all competitive distances from 800 meters to the marathon,” Anderson says. “The problem was not that the European runners had suddenly begun to run slowly, but African runners, particularly the Kenyans, were running extraordinarily fast times.”
The majority of Kenyans competing at the elite level came from one rather small tribe of about three million people, the Kalenjins. “Observers of this transformation have been tempted to conclude that Kenyan runners have some inborn capacity for long-distance running,” Anderson explains. “In competitive running, nature seems to be winning out over nurture: Kenyans and other East African runners appear to have the right genes for elite performance.”
However, concluding that genetic differences are the paramount factor underlying success in endurance performance is premature. “In many cases, further analysis of the actions of specific genes reveals that the effects are not always consistent or that the genes that seem to have the biggest impact on performance are not necessarily monopolized—or even present—in groups of high-performing endurance runners,” Anderson says. “Many other possibilities for the determination of performance, such as training, are apparent.”
“Even the biggest advocate of nature over nurture must admit that training plays a large role in determining what the race clock reveals when a runner crosses the finish line,” Anderson adds. In the case of East African runners, there is considerable evidence that Kenyan training differs dramatically from the training carried out by endurance runners in other parts of the world.
According to Anderson, geneticists interested in performance often try to establish what is called heritability of a trait, or H2. But, research using the heritability model has revealed that heritable factors are important but not exclusive determinants of several physiological variables that contribute to success in endurance running. “Taken together, the heritability studies suggest that an individual's distance running capability is determined by both genetic and environmental factors, and the exact proportioning of influence is unknown,” Anderson says.
In Running Science, Anderson presents the latest research-grounded knowledge in running physiology, biomechanics, medicine, genetics, biology, psychology, and training and racing. For more information, see Running Science.