Androgen receptor CAG and GGN repeat polymorphisms influence performance in boys and girls

BACKGROUND: Shorter CAG and GGN androgen receptor (AR) repeat polymorphisms are associated with stronger androgen signaling, and therefore, could influence lean mass and exercise performance during growth. METHODS: Physical fitness and body composition were measured by standardized procedures and the length of CAG and GGN repeats was determined by PCR and fragment analysis in 152 boys (11.5 2.6 years; Tanner <5) and 116 girls (10.1 3.2 years; Tanner <5). Individuals were grouped as CAG short (CAGs) if harboring repeat lengths of <21 and CAG long (CAGL) if CAG >21. Moreover, subjects were grouped as GGN short (GGNs) if harboring repeat lengths of <23 and GGN long (GGNL) if GGN>23. RESULTS: No significant differences in anthropometrics and body composition were observed between either CAGs and CAGL groups and GGNs and GGNL groups. Boys harboring CAGs completed the 300 -meter test faster than their CAGL counterparts. Moreover, girls from the GGNL group showed a significant higher V02,,ax than those in the GGNs group. CONCLUSIONS: In summary, carrying a short allele of the androgen receptor CAG repeat polymorphism is associated to higher anaerobic performance in boys, whereas long alleles of androgen receptor GGN polymorphisms are associated to higher aerobic capacity in girls.