Muscle Composition
Sprinters and endurance athletes differ in the composition and the capabilities of their muscles. These differences may be influenced by both training decisions and genetic factors.
Brian, your genetic muscle composition is common in elite power athletes.
Studies have found that almost all elite power athletes (including sprinters, throwers, and jumpers) have a specific genetic variant in a gene related to muscle composition. You have the same genetic variant as these elite athletes.
What this means for you
For most people, lifestyle and training factors drive athletic performance. At the national and international levels of competition, the genetic variant in this report seems to make a difference in athletic success, but its role for non-elite athletes isn't completely understood.
Genetics and Muscle Composition
Muscles and genetics
About endurance athletes
Genetics isn't everything
This report does not diagnose any health conditions or provide medical advice. Consult with a healthcare professional before making any major lifestyle changes or if you have any other concerns about your results.
Muscle composition is influenced by a genetic marker in the ACTN3 gene.
The ACTN3 gene contains instructions for making alpha-actinin-3, a protein found in certain types of fast-twitch muscle fibers. Some people have a non-functional variant of the ACTN3 gene and do not produce the alpha-actinin-3 protein. However, most of the elite power athletes who have been studied (including sprinters, throwers, and jumpers) have the functional ACTN3 variant and do produce this protein.
You have one copy of the C variant and one copy of the T variant.
R577X
C
T
See all information
R577X
C
T
-
Biological explanation
The marker we tested comes in two different forms: C and T. The T version is non-functional, which means the ACTN3 gene can't produce the alpha-actinin-3 protein. This marker has been studied the most in individuals of European descent.
-
Typical vs. variant DNA sequence(s)
C
Typical SequenceSubstitutionT
Variant Sequence -
Percent of 23andMe customers with variant
Variant: T
European 68.7%African American 38.5%Ashkenazi Jewish 69.0%East Asian 69.8%Hispanic or Latino 76.0%South Asian 84.2%Middle Eastern 70.2% -
References [ 1, 3, 4, 7, 11, 15 ] ClinVar
*This test cannot distinguish which copy you received from which parent. This test also cannot determine whether multiple variants, if detected, were inherited from only one parent or from both parents. This may impact how these variants are passed down.
23andMe always reports genotypes based on the 'positive' strand of the human genome reference sequence (build 37). Other sources sometimes report genotypes using the opposite strand.
References
- Alfred T et al. (2011). "ACTN3 genotype, athletic status, and life course physical capability: meta-analysis of the published literature and findings from nine studies." Hum Mutat. 32(9):1008-18.
- Berman Y and North KN. (2010). "A gene for speed: the emerging role of alpha-actinin-3 in muscle metabolism." Physiology (Bethesda). 25(4):250-9.
- Druzhevskaya AM et al. (2008). "Association of the ACTN3 R577X polymorphism with power athlete status in Russians." Eur J Appl Physiol. 103(6):631-4.
- Eynon N et al. (2013). "Genes for elite power and sprint performance: ACTN3 leads the way." Sports Med. 43(9):803-17.
- Guth LM and Roth SM. (2013). "Genetic influence on athletic performance." Curr Opin Pediatr. 25(6):653-8.
- Lee FX et al. (2016). "How does α-actinin-3 deficiency alter muscle function? Mechanistic insights into ACTN3, the 'gene for speed'." Biochim Biophys Acta. 1863(4):686-93.
- Ma F et al. (2013). "The association of sport performance with ACE and ACTN3 genetic polymorphisms: a systematic review and meta-analysis." PLoS One. 8(1):e54685.
- MacArthur DG et al. (2007). "Loss of ACTN3 gene function alters mouse muscle metabolism and shows evidence of positive selection in humans." Nat Genet. 39(10):1261-5.
- MacArthur DG et al. (2008). "An Actn3 knockout mouse provides mechanistic insights into the association between alpha-actinin-3 deficiency and human athletic performance." Hum Mol Genet. 17(8):1076-86.
- Moran CN et al. (2007). "Association analysis of the ACTN3 R577X polymorphism and complex quantitative body composition and performance phenotypes in adolescent Greeks." Eur J Hum Genet. 15(1):88-93.
- North KN et al. (1999). "A common nonsense mutation results in alpha-actinin-3 deficiency in the general population." Nat Genet. 21(4):353-4.
- Vincent B et al. (2007). "ACTN3 (R577X) genotype is associated with fiber type distribution." Physiol Genomics. 32(1):58-63.
- Wilson JM et al. (2012). "The effects of endurance, strength, and power training on muscle fiber type shifting." J Strength Cond Res. 26(6):1724-9.
- Yan Z et al. (2011). "Regulation of exercise-induced fiber type transformation, mitochondrial biogenesis, and angiogenesis in skeletal muscle." J Appl Physiol. 110(1):264-74.
- Yang N et al. (2003). "ACTN3 genotype is associated with human elite athletic performance." Am J Hum Genet. 73(3):627-31.
- Zierath JR and Hawley JA. (2004). "Skeletal muscle fiber type: influence on contractile and metabolic properties." PLoS Biol. 2(10):e348.