Calcaneal quantitative ultrasound measurements in young male and female professional dancers

Abstract

The aim of this study was to assess the bone status of dancers using calcaneal quantitative ultrasound (QUS). Twenty-four male and 26 female dancers (aged 19-36 years) and 100 age- and sex-matched nonathletic controls were included in this study. QUS parameters (broadband ultrasound attenuation [BUA], speed of sound [SOS], quantitative ultrasound index [QUI], and estimated heel bone mineral density [eBMD]) were obtained for both heels in all subjects using a gel-coupled QUS device. Two-way analysis of variance, including the factors of dancing status and gender, revealed significant differences in all QUS parameters between the dancers and the controls (p < 0.001 for all), without a significant interaction with gender status. For each heel (right versus left), the mean QUI, BUA, SOS, and eBMD values of the male and female dancers were 22.0% vs. 20.9% and 16.6% vs. 16.0%; 21.6% vs. 24.1% and 13.2% vs. 14.3%; 2.3% vs. 2.0% and 1.7% vs. 1.7%; and 25.0% vs. 23.9% and 19.0% vs. 18.6% higher than those of the male and female controls, respectively. Analysis of covariance still revealed significant differences between the dancers and the controls after controlling for the influence of body mass index (p < 0.001). Furthermore, the finding that significant bilateral differences in BUA did exist in the controls but not in the dancers demonstrated site-specific effects of exercise on bone, indicating that it is the dance that improved bone properties. Calcaneal QUS, with a strong discriminative ability between those involved in professional dance and normally active individuals, emerges as an attractive technology for exploring the benefits of exercise on bone, which might be a challenge for those in the conditioning field, who need to identify those who need intervention in terms of bone status and promote participation in high-impact physical activity, such as dance, to enhance bone quality.