With the IAAF World Athletics Championships just concluded in Beijing, we ask the question: How much do genes affect your athletic potential? Genetic traits are passed down through generations and can determine many physical attributes such as height, body type, predisposition to diseases and perhaps athletic ability. The limits of the human body continue to be debated, as athletes shatter records and achieve feats that many people believed that a human being could not do.
There was a time when people thought that it was not possible to run 100 meters in 10 seconds, but in 2009, Usain Bolt ran it in an astonishing 9.58 seconds. Factors such as training and diet certainly play a large role in athletic performance, but research shows that genes can also determine how far you can go. Genetics can influence an individual’s strength, muscle fiber composition, muscle size, lung capacity, flexibility and aerobic capacity. The extent to which genes define athletic capability is unknown but most researchers agree that 50-70% of athletic potential comes from genetics. Of course, environmental factors should not be understated. Simply having a favorable genetic attribute will not compensate for a lack of training or proper diet when it comes to competition at the highest level. Many genes have been associated with increased athletic performance such as IGF-1 (Insulin Growth Factor-1) which repairs and builds up muscles, and the gene for EPO (erythropoietin) which increases blood oxygen level and endurance.
The best known and most studied athletic gene is the alpha-actin-3 or ACTN3 gene. ACTN3 is known as the “power gene”, and produces a protein that regulates the function of fast twitch muscle fibers. There are two variants of the ACTN3 gene: R577R and R577X. Studies show that a person who possesses two copies of the R variant produces a large amount of ACTN3 and therefore shows a positive association with ability in power sports (sprinting, weightlifting) while a person who possesses two copies of the X variant does not produce any ACTN3 and shows a positive association with endurance sports (distance running, swimming). A person who possesses one copy of each variant will produce an intermediate amount of ACTN3 and may therefore be best suited for sports that require both strength and endurance (soccer, cycling). Many companies now offer commercial genetic testing for the ACTN3 gene. This type of testing can help people to determine which sports or activities they may excel at.
Advances in our understanding of the genetic basis of athleticism, combined with the increasing availability of genetic testing can also open up the possibility of gene doping. Using the same techniques being investigated in gene therapy, it may someday become possible to edit an athlete’s genome in order to give them the combination of genetic traits best suited for a given sport. Although gene doping is currently illegal, the technology around gene editing is quickly advancing. Some scientists warn that it may only be a matter of time before this type of performance enhancement becomes commonplace in the Olympics and in athletics in general. To learn more about gene doping in sports, watch the video below: