The present study was designed to investigate the association between a polymorphism in vitamin D receptor (VDR) gene at the translation initiation site and mechanical loading on bone mineral density (BMD). In 237 young males, including 109 athletes engaged in weightbearing sports, 48 competitive swimmers and 80 non-athletic controls, VDR genotypes were detected by endonuclease Fok I (FF, Ff and ff) and BMD of whole body, lumber and femoral neck were measured. Interestingly, the differences in whole body BMD between athletes and controls depended on the VDR genotypes; enhanced BMD in weight-bearing athletes was found in FF and Ff but not in ff. When swimmers were compared with VDR genotypematched controls, lower BMD was observed only in FF. These findings suggest that the polymorphism in VDR gene at translation initiation site may interacts with mechanical loading to influence BMD, implying a new notion that the FF genotype appears to respond more sensitive to difference in mechanical load in regulating whole body BMD rather than to be a prediction factor of the high bone density suggested in previous reports.

DESCENTE SPORTS SCIENCE Vol.23/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE