Is ACTN3 harmful?

At high doses, ACTN3 is toxic and detrimental to force generation, to demonstrate gene doping with supposedly performance-enhancing isoforms of sarcomeric proteins can be detrimental for muscle function.

How common is ACTN3?

This variant form of the ACTN3 gene is very common in the general population. Approximately 20%-30% of the population (over 1 billion people worldwide) have two mutant genes (X/X genotype), and there is not any obvious effect on individuals who have either one or two copies of the variant gene.

Does ACTN3 affect running?

In addition to affecting exercise performance, ACTN3 genotypes might also influence exercise-induced muscle damage, particularly after endurance events such as marathon running. Indeed, the X-allele has been associated with higher levels of several markers of muscle damage after exercise in amateur athletes [17,18,19].

Does ACTN3 make you faster?

ACTN3 protein efficiency results in a higher proportion of fast-twitch muscle fibers, which allows fast muscle contractions for sprinting and high muscle strength. The most common polymorphism of the ACTN3 gene is R577X, a C-to-T base substitution of an arginine base (R) to a premature stop codon (X).

Is the ACTN3 a good predictive of sprint performance?

The fact that ACTN3 is associated with muscle strength and sprint performance doesn’t mean that it necessarily provides any useful predictive power.

How does the ACTN3 gene affect muscle function?

Several studies have also found that ACTN3 influences muscle function in the general population, with the ~18% of the population with two disrupted copies of the gene displaying slightly lower muscle strength and poorer sprint performance than individuals with at least one functioning copy of the gene.

How many ACTN3 copies do sprinters have?

At the highest levels of performance ACTN3 genotype certainly make a big difference: among Olympic-level sprinters the frequency of individuals carrying two disrupted ACTN3 copies is vanishingly low (less than 3%, compared to ~18% in the general population).

Is the loss of ACTN3 good for endurance?

There is also weaker evidence suggesting that the loss of ACTN3 actually increases endurance performance, although this is much less clear than the association with sprint performance.