A Genetic Perspective: Athleticism

“It’s just genetics.” 

When talking about athletic activities, this is a phrase that is commonly used to explain when one individual performs an athletic feat with far less effort or training than most others. In reality, it's hard to establish what actually contributes to creating a solid athlete without getting into environmental factors and individual habits. With genetics, however, we can attempt to predict which individuals will be more dominant in certain activities thanks to genetic markers. 

There are thousands of genetic markers that influence performance, including those that determine our height and our body type (shape and proportions). Of these genetic markers, there are two that have more numerous and more consistent findings from a research perspective.

The ACTN3 gene is associated with the production of the protein ɑ-actinin-3, which is a sarcomeric (contractile muscle fiber) protein found in type II (fast twitch) muscle fibers. Essentially, individuals with this gene will perform better in more explosive, short duration activities such as sprinting, jumping, throwing and lifting. A variation of this gene, called ACTN3 R577X, is associated with the production of a much shorter ɑ-actinin-3 protein, which breaks down in the muscles. As a result, individuals with this genotype are likely to excel in endurance type activities. Exhibiting this variant in both copies of the gene is known as 577XX, which leads to the absence of ɑ-actinin-3, in turn leading to a high proportion of slow twitch muscle fibers (Type I). In world class endurance athletes, this gene is highly prevalent. 

Another gene, known as ACE, is responsible for the production of an enzyme known as angiotensin-converting enzyme. This enzyme converts angiotensin I to angiotensin II, which is an important protein for the homeostatic control of blood pressure and, while not completely understood, exerts some effect on the musculoskeletal system. Polymorphisms of this gene produce two variants: type D and type I. The ACE I allele is associated with lower activity, and the ACE D allele is associated with higher levels of activity. Having two copies of the D polymorphism, or a DD genotype can be associated with better performance in power or strength type events or movements. An II genotype is affiliated with exercise efficiency, therefore it can be expected that individuals with this genotype will likely favor endurance type exercise. 

While these genetic markers are important, they aren’t everything. At the end of the day, as regular people or even as athletes we will never know without testing whether or not we exhibit some of these genes, therefore we should not allow the thought of them to discourage us from working hard and reaching our goals. As mentioned previously, genetics play an important role but in the same vein, so do our habits, our psychology and the people we surround ourselves with. 

Regardless, I think this is an interesting topic because as humans, we are always trying to push the envelope with regards to performance, and after witnessing some of the incredible athletic feats we are capable of we can’t help but wonder what makes some of these athletes so special.

Primary Source

Secondary Source