ORIGINAL ARTICLE  EPIDEMIOLOGY AND CLINICAL MEDICINE 

The Journal of Sports Medicine and Physical Fitness 2019 September;59(9):1564-70

DOI: 10.23736/S0022-4707.19.09700-7

Copyright © 2019 EDIZIONI MINERVA MEDICA

language: English

Bone mineral density in adolescent elite ballet dancers

Tim WIELANDT ^{1, 2}, Tim van den WYNGAERT ^{1, 3}, Johanna R. UIJTTEWAAL ^{1, 2}, Ivan HUYGHE ^{1, 3}, Michiel MAES ⁴, Gaëtane STASSIJNS ^{1, 2} ✉

¹ Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; ² Department of Physical Medicine and Rehabilitation, Antwerp University Hospital, Edegem, Belgium; ³ Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium; ⁴ Department of Neurology, Heilig-Hart Hospital, Lier, Belgium

BACKGROUND: Data documenting BMD in pre-professional adolescent ballet dancers is limited. This cross-sectional study assesses bone mineral density (BMD) in young adolescent elite ballet dancers and compares BMD values between males and females (with and without normal menarche) and body composition between dancers with and without low Z-score.
METHODS: Cross-sectional study of third year ballet students (female=23; male=15; mean age 14.7 years; SD: 0.5) of The Royal Ballet School of Antwerp (Belgium) training 22 hours a week. They completed questionnaires and underwent dual energy X-ray absorptiometry (DXA) to measure BMD and body composition. Each female participant completed questionnaires assessing menstrual status.
RESULTS: DXA revealed that 12 out of 38 (32%) of the dancers had Z-score <-1. On average, male dancers had a lower BMD compared to an age-matched reference population (mean Z-score -0.9; SD 0.5), with 7 out of 15 having Z-score <-1. Overall, absolute BMD values were highest in the legs, followed by spine and arms. Dancers with Z-score <-1 had a significantly lower total mass. 43% of female ballet dancers had not yet had their first period and 39% had oligomenorrhea, but no significant differences between groups was detected.
CONCLUSIONS: A third of adolescent elite ballet dancers had low to very low Z-score. Nearly 2 out of 3 dancers with a Z-score <-1 were males, showing that low BMD is not limited to female dancers. Among female dancers menstrual dysfunction was frequent, without apparent impact on BMD or body composition in the studied age group.

KEY WORDS: Dancing; Bone density; Amenorrhea; Musculoskeletal system; Injuries