Association between polymorphisms of vitamin D receptor gene ApaI, BsmI and TaqI and muscular strength in young Chinese women

The association between the polymorphisms of vitamin D receptor gene ApaI, BsmI and TaqI and isokinetic muscular strength was examined in 109 healthy, young Chinese women. Methods: Genomic DNA was extracted from mouthwash samples and vitamin D receptor genotypes were determined with the established methods. The peak torque of the dominant limb in concentric and eccentric knee extensors and flexors and elbow extensors and flexors was measured using Cybex-Norm-770 isokinetic dynamometer at slow and fast velocities. The distribution frequency of vitamin D receptor gene alleles was analyzed by chi-square test. The difference in muscular strength between VDR genotype groups was analyzed using one-way ANOVA. The ApaI, BsmI and TaqI alleles and genotype frequencies appeared to be in a Hardy-Weinberg equilibrium. Subjects with the vitamin D receptor ApaI null (A allele) mutation (AA) exhibited significantly lower knee and elbow concentric or eccentric peak torque than those with aa homozygous or Aa heterozygous. The BB & Bb group showed significantly higher peak torque in concentric knee flexors than bb group. No association was found between vitamin D receptor gene TaqI and muscular strength. The data indicated that vitamin D receptor gene ApaI and BsmI polymorphisms rather than TaqI polymorphism might be associated with muscular strength.