Individuals with mental retardation (MR) may have high risks of low bone mass, however, a few previous studies are available. The purpose of this cross-sectional study was to measure the bone mass of athletes with MR (MR athletes) participated from about 80 countries in 2005 Special Olympics World Winter Games in Nagano, Japan.
　Asian and Caucasian MR athletes (89 females and 321 males; aged 10-52 and 9-52, respectively) were recruited. Quantitative ultrasound at os calcis was measured by using Achilles A1000 EXPRESS (GE Lunar) and the bone status was expressed as‘Stiffness’ index (SI), which has been shown to have the best correlation with bone mineral density.
　The differences in mean SI of each age between MR athletes and age-matched healthy reference group (healthy references) were higher tendency in female MR athletes in Asia than in healthy references, while there was no differences in males, and it was observed that higher tendency in female and male MR athletes in Caucasian than in healthy references. The differences of mean SIs were higher in Caucasian MR athletes than in Asian.
　These results suggested that the bone mass of athletes with MR who attended Special Olympics might be similar to that of individuals without MR, and to continue physical activity should be important for prevent osteoporosis in individuals with MR.

DESCENTE SPORTS SCIENCE Vol.27/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE