Power, endurance and the ACTN3 gene
Some bodies are built for explosive power and others for endurance. One of the clearest genetic signals behind that difference is the so-called speed gene, ACTN3.
ACTN3 · R577X (rs1815739)Why can one person sprint and jump naturally while another excels at distance? Training and dedication matter most, but genetics set a starting tilt, and ACTN3 is one of the best-studied examples.
ACTN3 builds fast-twitch muscle
The ACTN3 gene makes alpha-actinin-3, a structural protein found specifically in fast-twitch muscle fibres, the fibres responsible for rapid, forceful, explosive contractions used in sprinting, jumping and heavy lifting.
The R577X variant
The variant R577X (rs1815739) determines whether you make this protein. The R allele is functional; the X allele is not. RR and RX carriers produce alpha-actinin-3 and tend toward power and sprint ability, while XX carriers, around 18% of people, make none of it and lean more toward endurance.
What it means for training
This is a tilt, not a verdict: XX athletes can absolutely train for power, and RR athletes can build endurance. But knowing your type helps you lean into your natural strength, set realistic expectations, and adjust how much recovery your fibre profile needs.
Your ACTN3 type tilts you toward power or endurance. Train to your genetic strengths, and match recovery and nutrition to the load.
What actually helps
Beyond aligning training emphasis, intense athletes of any genotype have higher needs for antioxidants, B-vitamins and electrolytes to match the oxidative and metabolic load of heavy training, which is exactly what a performance-focused analysis adjusts for.
The science, in depth
ACTN3 R577X (rs1815739) introduces a premature stop codon; the XX genotype produces no alpha-actinin-3, which is compensated by alpha-actinin-2 but with a shift in fast-twitch fibre properties. The X allele is markedly under-represented in elite sprint/power athletes and over-represented in some endurance contexts, making ACTN3 a robust power-versus-endurance marker.
Go deeper
Everything behind this Gene Story: what your personal report shows, Dr. Wallerstorfer’s explanation, and the full scientific review.
Your report chapter
Your Performance analysis covers muscle-development and endurance genes, with training guidance and food ratings adapted for a higher training load.
See what the analysis covers →Dr. Wallerstorfer explains it
A short lecture on how your genes shape muscle development, power and endurance.
Scientific review
The full internal Novogenia laboratory review on athletic-performance genetics is available to partners on request.
Your personal Performance report
This Gene Story is one chapter of the Performance analysis, where it appears with your own genotype, a colour-coded verdict and recommendations tailored to you.
See your own performance genetics
A single DNA analysis shows whether you are tilted toward power or endurance, and how to train for it.
Explore the Performance analysis →