Androgen receptor gene microsatellite polymorphism is associated with muscle mass and strength in bodybuilders and power athlete status.

Background: The androgen receptor ( AR ) gene contains a polymorphic trinucleotide (CAG) microsatellite repeat sequence (short or long alleles) that has been associated with fat-free mass in untrained men, which needs to be replicated in athletic cohorts.
Aim: The purpose of this study was to explore the AR (CAG) _n polymorphism in trained individuals.
Subjects and Methods: A total of 61 professional bodybuilders (40 males, 21 females), 73 elite male sprinters and weightlifters and 186 male controls were enrolled in this study. The influence of the AR (CAG) _n polymorphism on muscle mass and strength was assessed in bodybuilders, while the frequencies of AR (CAG) _n alleles were compared between power athletes and non-athletes.
Results: The polymorphism was associated with anthropometric and strength measurements in bodybuilders of both genders. Those with ≥21 CAG repeats (i.e. carriers of long alleles) exhibited greater ( p  < 0.05) body mass index, absolute muscle mass, arm/thigh circumference and upper/lower limb strength compared to those with <21 CAG repeats. Furthermore, carriers of ≥21 CAG repeats were more frequent among power athletes compared to controls ( p  = 0.0076).
Conclusions: Long alleles of the AR (CAG) _n polymorphism were associated with greater muscle mass and strength in bodybuilders, and power athlete status.