There is concern that child participation in artistic gymnastics training has adverse consequences on growth and development. While there is a widespread notion that gymnastics participation is linked to poor diets, disordered eating, secondary amenorrhea, and bone loss, the scientific evidence supporting this contention is lacking. Despite low calcium, energy restricted diets and a history of menstrual disruptions, college gymnasts have higher bone mineral density (BMD) than controls. Elevated BMD in premenstrual gymnasts suggests that early gymnastics training, prior to the onset of puberty, is critical in the development of peak bone mass. However, it is possible the enhanced BMD exists before training ever begins. The investigator's main hypothesis is that high-levels of artistic gymnastics training initiated at a young age will enhance BMD. A second hypothesis is that high-levels of artistic gymnastics training initiated at a young age will not promote energy restriction, low calcium intakes or relevant psychological symptoms of disordered eating. There is also concern that gymnastics participation results in a reduced height. A reduction in predicted height and growth velocity and lower insulin-like growth factor 1(IGF-1) levels have been found in gymnasts. However, no studies have examined IGF-1 in gymnasts over time, nor have simultaneous changes in height and growth factors been examined in gymnasts. In addition, no studies have determined whether growth factor levels in gymnasts are lower than nongymnasts prior to the onset of training. A third hypothesis is that high-levels of artistic a gymnastics training initiated at a young age will blunt growth velocity and alter IGF-1 and IGF-1 binding protein-3 (IGFBP-3). To test these hypotheses, girls (5-8 years of age) will be examined during their first two years of gymnastics training. The specific objectives of the proposal are: 1) to determine if elevated BMD is present before gymnastics training is initiated; 2) to determine the impact of early gymnastics training on BMD, dietary intakes and relevant psychological symptoms of disordered eating behavior; 3) to determine the basis for elevated BMD in gymnasts by assessing growth factors, markers of bone turnover and sexual maturation; and 4) to determine if two years of gymnastics training will blunt growth velocity or alter growth factors. This study will provide insight into the impact of gymnastics activity initiated at an early age on bone and growth in children.
