Differences in Bone Mineral Density and Associated Factors in Dancers and Other Female Athletes.

Abstract

Dancers are susceptible to Relative Energy Deficiency in Sport (REDs), specifically low total body areal bone mineral density (aBMD). Little is known about how dancers' BMD compares to other athletic populations. The objective of this study was to examine the association between participant characteristics and aBMD among female pre-professional dancers compared to other female athletes. 269 females [132 dancers [17.6 (3.2) years] and 137 sport participants [22.8 (2.6) years] were included in this study. aBMD (g/cm2) was estimated using dual X-ray absorptiometry. Multivariable linear regression was used to examine the association between height adjusted z-scores of aBMD (aBMD-Z) and age (years), body mass index (BMI) (z-score), supplement intake, history of stress fracture, irregular menses, MRI/bone scan, one-year injury history, oral contraceptives, and activity (dance/sport). Total body aBMD and aBMD-Z were lower in dancers than athletes [dancers: aBMD=1.03 g/cm2 (95% CI: 1.01, 1.05); aBMD-Z=-0.28 (-0.43, -0.12)(p<0.001); athletes: aBMD=1.14 g/cm2 (95% CI: 1.12, 1.16); aBMD-Z= 0.41 (0.25, 0.57) (p<0.001)]. aBMD-Z increased with age (β=0.054, 95% CI: 0.017, 0.092; p=0.004) and BMI (β=0.221, 95% CI: 0.006, 0.415; p=0.043). Activity type modified the relationship between BMI and aBMD-Z (β=0.323, 95% CI: 0.025, 0.621; p<0.033) with a stronger positive association in dancers, compared to other female athletes. Dancers had lower total body aBMD and aBMD-Z than other female athletes. aBMD-Z increases with age in both groups. A stronger association exists between aBMD-Z and BMI in dancers than athletes. Future studies should consider changes in aBMD-Z during adolescence and associations with increased risk of bone injury.