title: The alpha-actinin-3 r577x polymorphism and physical performance in soccer players.
abstract: BACKGROUND
  The aim of this study was to investigate the association between ACTN3 genotype (RR, RX, and XX) and physical performance of 138 adult, professional, U-20 and U-17 years Brazilian first-division soccer players.
  
  
  METHODS
  The following three parameters were investigated: first, speed, using a 30-meter sprint test with speed measured at 10 meters, 20 meters, and 30 meters; second, muscular strength, using counter-movement-jump and squat jump tests; and third, aerobic endurance using the Yo-Yo endurance test. The athletes were ranked in ascending order according to their performance in each test. After which they were divided into quartiles and clustered according to genotype and allele frequency. The χ2 was used to compare the genotype frequencies (RR, RX and RR) and allele frequencies (R and X) within and between the different quartiles of performance rating.
  
  
  RESULTS
  No significant differences were observed in genotypic or allelic frequencies between different performance ratings. The ACTN3 genotype was not associated to any of the physical performance parameters.
  
  
  CONCLUSIONS
  Our study provides no ervidence for an assocviation between alpha-actinin-3 R577x genotypes and differences in physical performance in adult, professional, U-20 and U-17 years Brazilian first-division soccer players.
authors: Desportive Center of Federal University of Ouro Preto, Ouro Preto, Brazil - danielcoelhoc@gmail.com.
authors: Daniel B
authors: DB
authors: Coelho
authors: Eduardo
authors: E
authors: Pimenta
authors: Izinara C
authors: IC
authors: Rosse
authors: Christiano
authors: C
authors: Veneroso
authors: Lenice K
authors: LK
authors: Becker
authors: Maria R
authors: MR
authors: Carvalho
authors: Guilherme
authors: G
authors: Pussieldi
authors: Emerson
authors: E
authors: Silami-Garcia
mesh_terms: D000185:Actinin / Q000235:genetics*; D000293:Adolescent; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D001938:Brazil; D005080:Exercise Test; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic; D012916:Soccer / Q000502:physiology*; D055815:Young Adult
chemical_list: C118456:ACTN3 protein, human; D000185:Actinin