ACTN3 and Muscle Performance

Tuesday, August 27, 2019. Author FitnessGenes

ACTN3 and Muscle Performance

ACTN3 is the famous “gene for speed”. 

It codes for a protein called alpha-actinin-3, which supports high-velocity, forceful contraction of fast-twitch (Type II) muscle fibers. 

One variant of the ACTN3 gene, the R allele, results in production of the alpha-actinin-3 protein and is significantly more common in strength, power and sprint athletes – hence the “gene for speed” moniker.

By contrast, people carrying two copies of the X allele / variant do not produce any alpha-actinin 3 protein at all. Approximately 18% of the global population fall into this group, who we term as having alpha-actinin 3 deficiency

While it has no negative health effects, alpha-actinin 3 deficiency is thought to be a disadvantage when it comes to elite athletic performance in sprint and power events. On the plus side, burgeoning evidence suggests that alpha-actinin 3 deficiency may be advantageous for longer-duration endurance exercise. 

To find out more this and other personalized traits, login to truefeed or sign up for a FREE truefeed account.  

Need help choosing a plan?

Use our Plan Advisor to determine which genetically tailored diet and exercise program best fits your needs.

Find out
Sign up

Newsletter sign up

Sign up to receive our FREE newsletter and emails featuring articles on genetics, exercise, nutrition, customer success stories, new product information and promotional offers.

You're signed up

Thanks for signing up to the FitnessGenes newsletter, we’ll keep you up to date with our latest news and offers.

Quick links for testing on stage

Some technical debug stuff


X-Forward =,
Remote-Addr =
Your IP Address =,
Override location = =>
Override pricetable = =>
Your Continent = NA - North America
Your Country = US - United States
Your State = CA - California
Your City = - Los Angeles
Your Price Table = USD
Location comments = Fallback due to The specified IP address was incorrectly formatted:,