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.
Source: 1000 Genome Project. Global averages for both sexes
There are two different versions of the ACTN3 gene that we analyse for you: the C (or R) version and the T (or X) version.
Associated with greater muscle strength and power, the C (or R) version of the ACTN3 gene has been found in almost every single Olympic 100m runner ever tested. An association has also been observed between the TT (or XX) genotype and endurance capability, although this link does not appear to be as strong.