Kaufman, Beth C.2009-01-292009-01-292008-12https://hdl.handle.net/11299/47096University of Minnesota Ph.D. dissertation. December 2008. Major: Kinesiology. Advisor: Moira A. Petit Ph.D. 1 computer file (PDF); xiii-132 pages, appendices.lthough skeletal development is globally determined by genetic factors early in life, hormonal status and mechanical loading are also important determinants of bone development, peak bone mass accrual, rates of bone turnover, as well as rate of bone loss prior to menopause. Bone is thought to adapt its strength primarily to mechanical demands from growth, changes in muscle force and physical activity. The effects of mechanical loading seem to primarily effect the periosteal growth of the loaded bones, increasing modeling and remodeling on the periosteum, which increases overall bone strength. Other factors, specifically sex steroids, may influence bone loss by mediating the impact of loading on bone by altering the sensitivity of the periosteal and/or endosteal surfaces to loading. Women in this age range (18-30) are often overlooked in bone research. Therefore, in these studies, we use pQCT to assess cortical and trabecular bone vBMD, bone geometry and estimates of bone strength. thus provides the first pQCT human evidence of: 1) the relationship between measures of estrogen and measures of bone geometry and strength and 2) the effects of subtle changes in menstrual cycle characteristics on bone radial vBMD and tibial area and strength. The results suggest that measures of mechanical load are the greatest predictor of bone density in strength in young adult women, and other factors such as hormonal characteristics and nutrition have a smaller role in bone strength and density.en-USAreal Bone Mineral DensityBendingBone GeometryCross-sectional Moment of InertiaKinesiologyThesis or Dissertation