The Influence of Intense Ballet Training on Trabecular Bone Mass, Hormone Status, and Gonadotropin Structure in Young Women

A cross-sectional study on young dancers and exdancers was performed to evaluate the effects of intense weight-bearing exercise and dietary restriction, started during puberty, on bone mineral density (BMD), menarche age, menstrual function, and gonadotropin structure. Twenty current dancers (group 1) and 9 exdancers (group 2) were compared with a control group of 30 age-matched, regularly cycling women. Body weight, body mass index, total daily caloric intake, and nutritional markers were significantly lower (P < 0.05) in groups 1 and 2 than in controls. Using Quantitative Computed Tomography for the BMD evaluation, 12 dancers and 5 exdancers had Z-scores less than 2.5 sd below the mean of the controls; whereas, in 6 dancers and in 2 exdancers, BMD was between 1 and 2.5 sd. Groups 1 and 2 had a delay of menarche, which correlated positively with years of dance before menarche (r = 0.8; P < 0.001). Dancers had low levels and altered structure of circulating gonadotropins, which improved after GnRH stimulation. In conclusion, ballet training performed by dancers during puberty, dietary restriction, and low body mass index can all be associated with reduction in BMD and altered gonadotropin isoforms, with subsequent delay of menarche, menstrual dysfunctions, and insufficient peak bone mass. A longitudinal study must be conducted to confirm the persistence of low lumbar spine bone density in adult age.