J Dance Med Sci. 2011;15(3):99-107.
Ducher G, Kukuljan S, Hill B, Garnham AP, Nowson CA, Kimlin MG, Cook J.
Noll Laboratory, Department of Kinesiology, Pennsylvania State University, University Park 16802, USA. gaele.ducher at hotmail.com
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.
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Small group of male youths danced indoors at least 6 hours per week
Perhaps they did not have enough bone-building co-factors to build BMD.
See It takes more than just Vitamin D to build bones which include the following list
- Calcium: 500 mg daily
- Magnesium: 500 mg daily
- Vitamin K2: 5-10 mg daily
- Boron: 5-10 mg daily
- Silicon: 2 mg daily
- Strontium: 10 - 100 mg daily - confusion
- All items in Category Bone Health and Vitamin D 105 items as of March 2012