Role of impact activity in peripubertal bone accrual

达到最大峰值骨量是预防骨质疏松症的关键。由于大部分骨量是在青春期前几年积累的，因此旨在增加峰值的干预措施应针对这一时期。体力活动是一个重要的可改变的因素，有助于骨积累，但目前还不清楚是否在儿童时期积累的好处保持骨骼成熟。该提案检验了以下假设：（I）参加撞击活动的女孩在青春期期间比不活动的女孩积累更多的骨量，即使在活动停止后也会保留这些益处;（II）骨几何形状的增加比骨材料性质的增加对骨量增加的贡献更大。为了检验这些假设，提出了以下具体目的：（I）为了纵向测量青春期前和青春期前后体操运动员、退役体操运动员和非体操运动员对照组的骨增长和冲击活动量，将从平均11年开始跟踪3年。每周的体操活动时间将被记录，身体活动量将通过问卷调查来测量。在基线和6个月间隔时，将进行人体测量，记录自我Tanner阶段，并进行半定量食物频率问卷调查。每年进行一次生物电阻抗分析，测量肌肉力量和耐力，并进行双能X线吸收测定法（DXA）扫描。(II)纵向测量相同活动组和对照组的骨几何结构和骨矿物质性质。DXA扫描将用于评估骨几何结构以及骨和对照队列的差异。DXA扫描将用于评估骨几何结构和骨体积密度活动与非活动儿童的差异。证实所提出的假设将肯定的重要性，儿童活动在骨积累，提供证据的保护作用，这种活动。

Attainment of maximal peak bone mass is crucial in the prevention of osteoporosis. Because a majority of bone mass is accrued during the peri- pubertal years, intervention designed to increase the peak should target this period. Physical activity is an important modifiable factor contributing to bone accrual, yet it is unclear whether benefits accrued during childhood are maintained to skeletal maturity. This proposal tests the following hypotheses: (I) Girls who participate in impact activity will accrue greater amounts of bone during the peripubertal years than inactive girls, and will retain those benefits even after cessation of the activity; (II) Increases in bone geometry will provide a greater contribution to bone mass gain than increases in bone material properties. To test these hypotheses the following Specific Aims are proposed: (I) To longitudinally measure bone accrual and the amount of impact activity in a cohort of pre- and peri-pubertal gymnasts, retired gymnasts, and non- gymnast controls will be followed for a 3 year period, beginning at an average of 11 years. Hours per week of gymnastics activity will be recorded and amount of physical activity will be measured by questionnaire. At baseline and six month intervals anthropemetric measurements will be made, self-Tanner stage will be recorded, and a semi-quantitative food frequency questionnaire will be administered. At yearly intervals bioelectric impedance analysis, muscle strength and endurance will be measured, and dual energy x-ray absorptiometry (DXA) scans will be performed. (II) To longitudinally measure bone geometry and bone mineral material properties in the same activity and control cohorts. DXA scans will be used to assess differences in bone geometry and in bone and control cohorts. DXA scans will be used to assess differences in bone geometry and in bone volumetric density activity vs. inactive children. Confirmation of the proposed hypotheses will affirm the importance of childhood activity in bone accrual, providing evidence of the protective effect of such activity.