Received January 31, 2005
Revised March 8, 2005
Accepted after revision May 5, 2005

¹ University of Maryland
² Children's National Medical Center
³ University of Pittsburgh
⁴ United States Department of Agriculture
⁵ University of Maryland,

^* To whom correspondence should be addressed. E-mail: kstith{at}umd.edu.

	Abstract

To determine the influence of the vitamin D receptor (VDR) gene FokI and BsmI genotype on bone mineral density response to two exercise training modalities, 206 healthy men and women (50-81 yrs) were studied before and after ~ five to six months of either aerobic exercise training (AT) or strength training (ST). One hundred and twenty-three subjects completed AT (n = 51 men & 72 women) and 83 subjects completed ST (n = 40 men & 43 women). DNA was extracted from blood samples of all subjects and genotyping was performed at the VDR FokI and BsmI locus to determine its association to training response. Total body, greater trochanter, and femoral neck bone mineral density (BMD) was measured before and after both training programs using dual-energy x-ray absorptiometry. VDR BsmI genotype was not significantly related to BMD at baseline or after ST or AT. However, VDR FokI genotype was significantly related to ST- but not AT - induced changes in femoral neck BMD (P < 0.05). The heterozygotes (Ff) in the ST group approached a significantly greater increase in femoral neck BMD (P = 0.058) compared to f homozygotes. There were no significant genotype relationships in the AT group. These data indicate that VDR FokI genotype may influence femoral neck BMD response to ST, but not AT. Key Words: exercise training, genetics, bone, polymorphism, osteoporosis

Key Words: Ageing, Bone, Exercise