INSULIN-LIKE GROWTH FACTORS AND BONE IN YOUNG FEMALE GYMNASTS

(Under the Direction of RICHARD D. LEWIS) The effects of 24-months of recreational artistic gymnastics participation on plasma insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-3 (IGFBP-3) and bone were assessed in prepubertal females, four to eight years of age, with no history of sports participation. Over 24-months, log IGF-I, IGFBP-3 and IGF-I/IGFBP-3 increased in gymnasts (n=48) and controls (n=66). When gymnasts and controls were combined, the 24-month log IGF-I and total body bone area, bone mineral content (BMC) and areal bone mineral density (aBMD), lumbar spine BMC and aBMD, femur BMC and aBMD, narrow neck cross sectional area (CSA), intertrochanteric CSA and section modulus (Z) and shaft Z were correlated. Negative correlations were observed between hours of gymnastics participation and the 24-month gain in log IGF-I, IGFBP-3 and IGF-I/IFGBP-3. The lack of a marked IGF response and the small bone response to participation in recreational artistic gymnastics in the current project may be partially related to the young age of participants