Exercise and Calcium Effect on Pubertal Bone Gain

骨质疏松症是一个主要的公共卫生问题。 在这个应用中，我们建议扩展我们的研究，负重体力活动和高钙饮食对青春期女孩骨质量增加的影响。 由于很少有已知的安全，有效的方法来恢复失去的骨到骨质疏松的骨骼，预防骨质疏松症是至关重要的。 如果骨骼发育能够在生长过程中得到最大化，年轻人将在开始成年时具有最佳的骨骼质量，并且在以后的岁月中不太可能患上骨质疏松症。 然而，青年人的骨骼健康问题尚未得到充分解决。 本实验研究的目的是：1）测试负重锻炼计划对青少年女性骨质量增加的影响; 2）比较负重锻炼计划与负重锻炼计划和高钙饮食对青少年女性骨质量增加的影响。待检验的主要假设为：1）完成负重锻炼计划的青少年女性将比保持其通常活动水平的青少年女性具有更高的脊柱BMC和跟骨SOS，和2）完成负重运动计划和1500 mg/kg高钙饮食干预的青少年女性。一天的青少年女性将有更高的脊柱BMC和跟骨SOS比谁完成了锻炼计划，但保持其通常的钙摄入量。 我们将对107名10-13岁的女性进行为期四年半的随访。 他们被随机分配到3组中的1组：1）每周进行3次负重锻炼的人，他们吃日常饮食（目前n=35）; 2）每周3次的负重锻炼计划中的那些人，并给予高钙食物以提供1500 mg/天（目前n=35）;或3）对照组，其消耗其常规饮食并维持其常规活动水平（目前n=37）。 每半年和研究结束时，对所有受试者进行脊柱、髋关节、桡骨和全身BMC、跟骨SOS、身高、体重、坦纳分期以及病史和社会史测量。 将每三个月和研究结束时评估一次膳食摄入量和体力活动。 对我们研究数据的中期分析表明，与单独进行体力活动或对照组相比，高钙饮食和定期负重体力活动的结合显著增加了骨量增加。 如果这些发现成立，他们将提供强有力的支持，除了运动之外，钙在增加女性骨量方面的重要作用。

Osteoporosis is a major public health problem. In this application, we propose to extend our study of the effects of weight-bearing physical activity and a high calcium diet on increases in bone quality in pubertal girls. Since there are few known safe, effective methods for restoring lost bone to the osteoporotic skeleton, prevention of osteoporosis is crucial. If skeletal development can be maximized during growth, young people will begin adulthood with optimal bone quality and be less likely to develop osteoporosis in later years. Yet bone health of youth has not been adequately addressed. The aims of this experimental study are 1) to test the effect of a weight-bearing exercise program on increases in bone quality in adolescent females; and 2) to compare the effect of a weight-bearing exercise program with the effect of a weight-bearing exercise program and a high- calcium diet on increases in bone quality in adolescent females. The primary hypotheses to be tested are: 1) Adolescent females who have completed a weight-bearing exercise program will have higher spine BMC and calcaneal SOS than adolescent females who have maintained their usual activity level, and 2) adolescent females who have completed a weight-bearing exercise program and a high calcium diet intervention of 1500 mg/day will have higher spine BMC and calcaneal SOS than adolescent females who have completed the exercise program but have maintained their usual calcium intake. We will follow 107 females ages 10-13 years for an additional four and one-half years. They have been randomly assigned to 1 of 3 groups: 1) those in a weight-bearing exercise program which meets 3 times/week and who consume their usual diets (current n=35); 2) those in a weight-bearing exercise program which meets 3 times/week and are given high calcium foods to supply 1500 mg/day (current n=35); or 3) a control group who consumes their usual diet and maintains their customary activity level (current n=37). Measurements of spine, hip, radius and total body BMC, calcaneal SOS, height, weight, Tanner stage, and medical and social history will be made on all participants semiannually and at the end of study. Usual dietary intake and physical activity will be assessed every three months and at the end of study. Interim analysis of data from our study suggests that the combination of a high calcium diet and regular weight- bearing physical activity significantly increases bone mass gain compared to physical activity alone or to a control group. If these findings hold, they would provide strong support for the essential role of calcium in addition to exercise in maximizing bone mass in growing females.