A gene for speed

ACTN3 is the world’s most famous ‘gene for speed’. This gene encodes for α-actinin-3, a protein that has been linked to greater baseline strength, a protective effect against muscle damage, and an increase in fast-twitch muscle fibres. One particular version of ACTN3 has been found in almost every Olympic sprinter ever tested. Your FitnessGenes result will tell you if you carry the ‘sprinter’ version, the version linked to endurance or both.

There are two different versions of the ACTN3 gene that we analyse for you: the R version and the X version.

Associated with greater muscle strength and power, one particular version of this gene — the R version — has been found in almost every single Olympic 100m runner ever tested. An association has also been observed between the XX genotype and endurance capability, although this link does not appear to be as strong.

You can find more information about the ACTN3 gene in our member area at where you can also find your results and what this means for you after your DNA has been analyzed by us. Head over to the shop to order your Fitnessgenes DNA analysis and genetic training system


We have fully reviewed the impact of this gene and the genetic variant we analyse as part of our scientific research process. You can access the full citation list on all studies reviewed here.

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