Bone Growth, Mechanical Stimulus and IGF-I

Abstract : Available data indicate that the genetic susceptibility for low bone mass is present very early in life. The aim of this project is to establish whether bone acquisition in teenagers who have sustained a fracture and have low bone mass can be enhanced by changing environmental factors, such as mechanical loading. The effects of a twelve-month mechanical intervention on musculoskeletal development will be studied and the results will be compared to matched teenagers undergoing either a classic resistance exercise intervention or no intervention. This study also examines the possible relations between the cross-sectional properties of bone and circulating levels of IGF-I, JGF-binding protein-3, and IGF-I genotypes in teenagers ages 16 to 18 years with sport-related fractures. The possible relations between bone acquisition induced by mechanical stimulus and circulating levels of IGF-I and the IGF-I genotype will be assessed. Recruitment for eligible teenagers for the first phase of this project, the cross-sectional arm in female subjects, began shortly after the approval of the project for human subjects research by the HSRRB and the local IRB on June 14, 2002. As of September 9, 2002, eight subjects have enrolled and completed the cross-sectional study, and seven more have scheduled appointments. Completion of this cross-sectional arm should occur in nine months with the longitudinal arm commencing immediately thereafter.