[Purpose] Association of ACTN3 polymorphism with bone mineral density and the physical
fitness of elderly women is still unclear. Therefore, this study investigated the
association between ACTN3 genotype and bone mineral density, and the physical fitness of
elderly women. [Subjects and Methods] Sixty-eight elderly women (67.38 ± 3.68 years) were
recruited at a Seongbuk-Gu (Seoul, Korea) Medical Service Public Health Center.
Measurements of physical fitness included muscle strength, muscle endurance, flexibility,
agility, balance and VO2max. Bone mineral density (BMD), upper limb muscle
mass, lower limb muscle mass, percent body fat and body fat mass for the entire body were
measured by dual-energy X-ray absorptiometry and an analyzer. Genotyping for the ACTN3
R577X (rs1815739) polymorphism was performed using the TaqMan approach. [Results] ACTN3
gene distribution of subjects were in the Hardy-Weinberg equilibrium (p=0.694). The
relative bone mineral density trunk, pelvis and spine differed significantly among the
ACTN3 genotypes. There were no significant differences among bone mineral densities of the
head, arms, legs, ribs and total, but the RR genotype tended to be higher than other
genotypes. Physical fitness was not significantly different among the ACTN3 genotypes.
[Conclusion] These results suggest that ACTN3 gene polymorphisms could be used as one of
the genetic determinants of bone mass in elderly women, and in particular, they indicate
that individuals with the RR genotype have higher BMD and bone mineral composition.