{{Genotype
|rsid=1815739
|allele1=C
|allele2=C
|magnitude=2.2
|repute=Good
|summary=Better performing muscles. Likely sprinter.
}}
This genotype indicates better performing muscles, {{PMID|18043716}} particularly for sprinting and power sports. Fast-twitch muscle fibers are able to produce alpha-actinin-3. Professional sprinters usually have this, although it is less common for endurance athletes.