Total and regional bone mineral content in Spanish professional ballet dancers

Associations between nutrition, energy expenditure and energy availability with bone mass acquisition in dance students: a 3-year longitudinal study

Three years of study showed that female and male vocational dancers displayed lower bone mass compared to controls, at forearm, lumbar spine and femoral neck. Energy intake was found to positively predict bone mass accruals only in female dancers at femoral neck. Vocational dancers can be a risk population to develop osteoporosis.

PURPOSE

To determine whether risk factors normally associated with low bone mass in athletic populations (i.e. nutrition intake, energy expenditure and energy availability) are significant predictors of bone mass changes in vocational dance students.

METHODS

The total of 101 vocational dancers (63 females, 12.8 ± 2.2 years; 38 males, 12.7 ± 2.2 years) and 115 age-matched controls (68 females, 13.0 ± 2.1 years; 47 males, 13.0 ± 1.8 years) were monitored for 3 consecutive years. Bone mass parameters were measured annually at impact sites (femoral neck, FN; lumber spine, LS) and non-impact site (forearm) using DXA. Nutrition (3-day record), energy expenditure (accelerometer), energy availability and IGF-1 serum concentration (immunoradiometric assays) were also assessed.

RESULTS

Female and male vocational dancers had consistently reduced bone mass at all anatomical sites (p < 0.001) than controls. IGF-1 did not differ between male vocational dancers and controls, but female dancers showed it higher than controls. At baseline, calcium intake was significantly greater in female vocational dancers than controls (p < 0.05). Male vocational dancers' fat and carbohydrate intakes were significantly lower than matched controls (p < 0.001 and p < 0.05, respectively). Energy availability of both female and male vocational dancers was within the normal range. A significant group effect was found at the FN regarding energy intake (p < 0.05) in female dancers. No significant predictors were found to explain bone mass differences in males.

CONCLUSION

Our 3-year study revealed that both female and male vocational dancers displayed lower bone mass compared to controls, at both impact and non-impact sites. The aetiology of these findings may be grounded on factors different than those usually considered in athletic populations.

Prevalence of low bone mineral density in female dancers

BACKGROUND AND OBJECTIVE

While some authors report that dancers have reduced bone mineral density (BMD) and increased risk of osteoporosis, others have stressed the positive effects of dance training on developing healthy BMD. Given the existing controversy, the aim of this systematic review was to examine the best evidence-based information available in relation to female dancers.

METHODS

Four databases (Web of Science, PubMed, EBSCO, Scopus) and two dance science journals (Journal of Dance Medicine and Science and Medical Problems of Performing Artists) were searched for relevant material using the keywords "dance", "ballet", "BMD", "bone density", "osteoporosis" and "female athlete triad syndrome". A total of 257 abstracts were screened using selected inclusion (studies involving bone measurements in dancers) and exclusion (editorials, opinion papers, chapters in books, narrative reviews and non-English language papers) criteria according to PRISMA guidelines. Following the above screening, a total of 108 abstracts were identified as potentially relevant. After the exclusion of conference proceedings, review papers, studies focusing only in male dancers and studies in which dancers' information were combined with other athletes, the eligible papers were subsequently assessed using the GRADE system and grouped according to: (1) prevalence of low BMD and associated factors, (2) incidence of low BMD and risk factors, (3) prevention/treatment of low BMD in dancers, and (4) other studies.

RESULTS

Of the 257 abstracts that were initially screened, only 35 studies were finally considered. Only one of these 35 was of high quality, while the remaining 34 were of relatively low quality. Seven studies reported prevalence of low BMD and associated factors, 10 reported associated factors with no prevalence data, while one reported prevalence with no associated factors data. One study cited risk factors, while another one elaborated on the treatment of low BMD in dancers. The remaining 15 studies were classified as "other studies".

CONCLUSIONS

It remains unclear whether low BMD is prevalent in female dancers. The present review highlights the need for high-quality BMD research in this area.

Total and regional bone mineral content in healthy Spanish subjects by dual-energy X-ray absorptiometry

DESIGN

This is an observational cross-sectional study.

OBJECTIVE

The aim of the present study was to describe and analyze patterns of change in total and regional bone mineral content in relation to age and gender in a sedentary Spanish sample population (from the Community of Madrid). The age range of the sample population was from birth to 80 years.

MATERIALS AND METHODS

One thousand one hundred twenty healthy subjects were recruited and divided into 16 groups according to age. Each subject underwent whole-body densitometry using dual-energy X-ray absorptiometry. An analysis was made of the amount of bone mineral content (BMC) in the whole body and in different regions: the head, trunk, upper limbs, and lower limbs.

RESULTS

Gender differences in mean values for upper limbs and lower limbs are statistically significant between 16 and 70 years of age. For the head and trunk, the mean BMC values show the most significant gender differences between 16 and 25 years of age (p <or= 0.001). Total bone mineral content (TBMC) and TBMC-to-height ratio show significant gender differences between 16 and 70 years of age. In females, TBMC values increase up to 20 years of age and in males up to 25 years of age.

CONCLUSION

We have determined an evolutionary normal pattern of bone mineral content in urban Spanish people.

The impact of a senior dancing program on spinal and peripheral bone mass

Because activity and regular exercise are important factors to maintain general good health in senior citizens, we investigated whether senior dancing has any effect on peripheral or lumbar bone density. We performed a prospective study over a12-mo period on bone density at a spinal and peripheral measuring site in 28 female senior members (mean age: 67 +/- 2 yr) of a dancing group in Vienna. Lumbar bone mineral density was assessed by quantitative computed tomography (qCT) and radial bone density by single photon absorptiometry of the distal forearm. The mean training time per week was 3.2 +/- 0.8 h. In the entire group of female dancers, no significant effects of dancing on radial or lumbar bone density could be observed. Linear regression analysis showed that the lower the qCT at the beginning of the observation period, the higher was the percentage increase of spinal qCT in the entire group during 12 mo of dancing (r = 0.52, P < 0.0001). For additional evaluation, females were divided into two subgroups, osteoporotic or nonosteoporotic, based on x-rays and lumbar bone mineral density (BMD) as measured by qCT. The group classified as dancers with osteoporosis (group I) showed a significant increase in lumbar bone density, whereas in the group of dancers without signs of osteoporosis (group II), BMD remained unchanged. Additionally, radial bone density did not show any changes in either group. Group I showed a significant correlation between basal spinal BMD and the percentage change of BMD during the observation period (r = 0.7, P < 0.001). Changes of the biochemical parameters were observed in the bone-specific isoenzyme of alkaline phosphatase, a marker of osteoblastic activity, in group I giving additional evidence of increased bone formation.