title: Vitamin D status and musculoskeletal health in adolescent male ballet dancers a pilot study.
abstract: Adequate vitamin D levels during growth are critical to ensuring optimal bone development. Vitamin D synthesis requires sun exposure; thus, athletes engaged in indoor activities such as ballet dancing may be at relatively high risk of vitamin D insufficiency. The objective of this study  was to investigate the prevalence of low vitamin D levels in young male ballet dancers and its impact on musculoskeletal health. Eighteen male ballet dancers, aged 10 to 19 years and training for at least 6 hours per week, were recruited from the Australian Ballet School, Melbourne, Australia.  Serum 25(OH)D and intact PTH were measured in winter (July) from a non-fasting blood sample. Pubertal stage was determined using self-assessed Tanner criteria. Body composition and areal bone mineral density (aBMD) at the whole body and lumbar spine were measured using dual-energy x-ray absorptiometry  (DXA). Injury history and physical activity levels were assessed by questionnaire. Blood samples were obtained from 16 participants. Serum 25(OH)D levels ranged from 20.8 to 94.3 nmol/L, with a group mean of 50.5 nmol/L. Two participants (12.5%) showed vitamin D deficiency [serum 25(OH)D level  < 25 nmol/L], seven dancers (44%) had vitamin D insufficiency (25 to 50 nmol/L), and the remaining seven dancers (44%) had normal levels (> 50 nmol/L). No relationship was found between vitamin D status, PTH levels, body composition, and aBMD. The most commonly reported injuries were  muscle tears and back pain. The average number of injuries reported by each dancer was 1.9 ± 0.4 (range: 0 to 5). There was no difference in the frequency of reported injuries between subjects with vitamin D deficiency or insufficiency (2.1 ± 0.6 injuries) and those with normal  vitamin D levels (1.4 ± 0.6 injuries). This pilot study showed that more than half of highly-trained young male ballet dancers presented with low levels of vitamin D in winter. Further investigations in larger samples of adolescent athletes are needed to determine if this could negatively  impact bone growth and place them at higher risk for musculoskeletal injuries.
authors: Noll Laboratory, Department of Kinesiology, Pennsylvania State University, University Park 16802, USA. gaele.ducher@hotmail.com
authors: Gaele
authors: G
authors: Ducher
authors: S
authors: S
authors: Kukuljan
authors: B
authors: B
authors: Hill
authors: A P
authors: AP
authors: Garnham
authors: C A
authors: CA
authors: Nowson
authors: M G
authors: MG
authors: Kimlin
authors: J
authors: J
authors: Cook
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D001315:Australia; D001823:Body Composition / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D002648:Child; D003615:Dancing / Q000502:physiology*; D006304:Health Status; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010865:Pilot Projects; D018570:Risk Assessment; D013472:Sunlight; D014808:Vitamin D Deficiency / Q000175:diagnosis* / Q000517:prevention & control