Decreased Bone Mineral Density in Forearm vs Loaded Skeletal Sites in Professional Ballet Dancers.

Abstract

To compare the differences in bone mineral density (BMD) at loaded and non-loaded skeletal sites in professional ballet dancers. We hypothesized that in both male and female elite ballet dancers, a significant difference in BMD will be observed between impact and non-impact sites. 44 elite ballet dancers, 22 men (age 26.4±5.9 yrs) and 22 women (age 24.9±5.3 yrs), were examined. BMD measurements were performed using dual-energy x-ray absorptiometry at three skeletal sites-forearm (FA), lumbar spine (LS), and femoral neck (FN)-and analyzed using t-tests, ANOVA, and linear regression models. Information about career duration, training volume, health habits, and menstrual disorders (women) was collected. Z-scores for LS and FN were significantly higher in men than in women. However, Z-scores for FA were similar in men and women and fell below the expected range for age (<-2.0), and they were significantly lower than those for LS and FN. With longer career duration, a trend was observed towards lower Z-scores for FN in men and towards higher Z-scores for FA in women. In ballet dancers, FA mineralization is extremely low compared to loaded skeletal sites. Male dancers may have lowered forearm BMD despite the absence of risk factors present in female dancers (menstrual disorders). Professional ballet dancers may be at risk of local osteopenia due to the "local non-impact" characteristics of ballet dance, and use of the 33% distal radius region for the accurate assessment of bone mineral status should be investigated further in this population.