SEASONAL CHANGES IN BONE TURNOVER IN ELITE FEMALE RHYTHMIC SPORTS GYMNASTS

Abstract

1860 The purpose of this study was to examine the seasonal changes in bone turnover in elite female rhythmic sports gymnasts (RSG). We studied eleven RSG (national class), aged 19-21 years and eleven normally active age-matched control volunteer subjects. The assessment was conducted on two occasions during in-season (competition) and off-season (reduced exercise training) periods in RSG. Bone turnover was assessed using a specific biomarker of bone formation (serum intact osteocalcin: I-OC), and a new biomaker of bone resorption, a 24 hr. urinary excretion of deoxypyridinoline (D-Pyr). Nutrition intake and menstrual cycle were assessed using questionnaires. There were no significant differences in energy intake between in-season and off-season. However, the off-season relative fatness was significantly higher compared with in-season (15.4±1.0 vs 19.2±3.0%). Also, off-season serum [Ca] in RSG was significantly greater than in-season [Ca] (8.8±0.3 vs 9.9±0.4 mg/dl). Off-season [D-Pyr] in RSG was significantly lower compared to the in-season. Inversely, [I-OC] during the off-season was significantly higher than that during the in-season, see figure. In comparison with the control group, RSG had a significantly higher [D-Pyr] and a significantly lower [I-OC] during the in-season. No significant differences were observed for [D-Pyr] between RSG and control groups during the off-season. These results suggest that an uncoupling of bone turnover between formation and resorption during the in-season was reversed during the off-season due, in part, to reduced exercise training.Figure