By Dev K. Mishra, M.D., President, Sideline Sports Doc
As I watch the Olympics this week I’m particularly interested in the stories about some of the athletes as kids, especially interviews with their parents. What was it in the child’s interests, determination, physical talents, or other circumstances that ultimately led them to the highest levels of their sport?
There are many factors that influence a child’s physical ability and athletic future, and some of those factors are genetic. More than 150 genes have been linked to different aspects of physical performance, including oxygen uptake efficiency, aspects of heart performance, and muscle fiber composition.
I performed a Google search today and found more than 10 companies (first two pages of search only!) claiming to perform definitive genetic testing to help parents of young athletes determine a course of direction for their child, e.g. power/sprint sport or endurance sport. For most tests a swab is taken from the inside of the child’s cheek, sent to a company for analysis, and there you go.
The ACTN3 Gene Is Correlated To Some Types Of Athletic Performance
I’m going to set aside for today the ethical questions about whether this type of testing is right or wrong- smarter people than me can debate that. What we can talk about here is that one particular gene- the ACTN3- is in fact associated with athletic performance. Any one of us can have either 0,1, or 2 functioning copies of the ACTN3 gene. This gene produces a protein that helps to regulate the function of fast muscle fibers.
The overly simplified version of the protein’s importance is this:
- Two working copies of the gene are found in many elite level sprinters or power sport athletes
- One working copy of the gene is also found in many elite level sprinters or power sport athletes
- Almost no elite level sprinters or power sport athletes have zero working copies of the ACTN3 gene, but many endurance sport athletes have zero working copies
…But None Of The Gene Combinations Predict Future Athletic Success
A key point about the studies performed to date is that most of these are observational (one point in time) or retrospective. No studies have been performed that followed children with the gene copy combinations into adolescence or adulthood to see how they turned out as athletes. Therefore our current level of knowledge does not allow us to predict future athletic success based on our genetics.
Take a further look at estimates of the ACTN3 gene copies in the general population: around 30% have two functioning copies of the gene (found in sprinters), about 18% have no functioning copies (found in endurance athletes), and about 52% of the population have one copy of each. Remember that professional athletes in all sports make up less than 1% of the population. So there is no ACTN3 combination that is unique to elite athletes; instead, whatever combination your child has, he or she will share that with many other people, and almost all of them will not be professional athletes.
Personally, I love the stories of players like Tom Brady, Kurt Warner, or Nancy Lopez- three who reached the top of their sports with supposedly less than ideal athletic abilities. If you’re interested in looking at your child’s (or your own) genetic profiles that’s up to you, just be realistic and understand that it’s just one part of your child’s overall potential.