The influence of ballet training on bone mass in Turkish ballet dancers

Ballerinas are known to be under risk for osteoporosis, both because of their poor nutrition and adverse effects of heavy exercise on menstrual cycles. We aimed to examine the risk factors for osteoporosis in Turkish ballet dancers, in a comparative cross-sectional study, to find out whether regular exercise effects bone metabolism. Twenty-two Turkish female ballet dancers and 20 female controls of comparable age and body mass index were studied. The outcome measure was the bone mass. Daily calcium intake and sex steroid levels were similar in both groups. Average hours of exercise per week were 27.2 +/- 7.6 for ballet dancers. Z scores or one mineral density (BMD) at lumbar spine and femoral area were significantly higher in dancers (lumbar BMD: -0.02 +/- 0.7 in dancers and -1.01 +/- 0.9 in controls; femoral BMD: 0.1 +/- 0.7 in dancers and -1.3 +/- 1.0 in controls; P < 0.001 for both). There was no significant difference in terms of Z scores in the forearm. In addition, both the right and left side calcaneal BMD T scores of dancers were higher than those of controls (P = 0.001 for each side). In the dancer group, calcaneal T scores of the supporting foot (dominant foot) were significantly higher than calcaneal T scores of the nondominant foot (P = 0.028 in the right dominant subgroup and P = 0.009 in the left dominant subgroup). Our results demonstrate that exercise is at least locally "bone saving" in ballet dancers under normoestrogenic conditions.