title: The ACTN3 R577X variant in sprint and strength performance.
abstract: OBJECTIVE
  The aim of this study is to examine the association between the distribution of ACTN3 genotypes and alleles in power, speed, and strength-oriented athletics.
  
  
  METHODS
  ACTN3 genotyping was carried out for a total of 975 Korean participants: top-level sprinters (n = 58), top-level strength athletes (n = 63), and healthy controls (n = 854).
  
  
  RESULTS
  Genetic associations were evaluated by chi-squire test or Fisher's exact test. In the power-oriented group composed of sprinters and strength athletes, the frequency of the XX genotype was significantly underrepresented (11.6%) in comparison to its representation in the control group (11.6% versus 19.1%, P < 0.05). When the power-oriented group was divided into strength-oriented and speed-oriented groups, no significant difference in the ACTN3 XX genotype was found between the strength-oriented athletes and the controls (15.9% versus 19.1%, P < 0.262). Only the speed-oriented athletes showed significant differences in the frequency distributions of the ACTN3 XX genotype (6.9% versus 19.1%, P < 0.05) from that of the controls.
  
  
  CONCLUSIONS
  The ACTN3 genotype seems to mainly affect sports performance and especially speed.
authors: Korea National University of Education, Chungcheongbuk-do, Korea.
authors: Hyeoijin
authors: H
authors: Kim
authors: Soonchunhyang University, Chungcheongnam-do, Korea.
authors: Keon-Hyoung
authors: KH
authors: Song
authors: Soonchunhyang University, Chungcheongnam-do, Korea.
authors: Chul-Hyun
authors: CH
authors: Kim
keywords: contractile property; fast-twitch muscle fibers; human performance; population genetics; α-actinin-3