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。在这项应用中，我们建议扩大我们对负重体力活动和高钙饮食对青春期女孩骨骼质量增加的影响的研究。由于目前尚无安全、有效的方法来修复骨质疏松的骨骼，因此预防骨质疏松至关重要。如果在生长过程中骨骼发育能够最大化，年轻人将以最佳的骨骼质量进入成年期，并在以后几年不太可能患上骨质疏松症。然而，年轻人的骨骼健康问题还没有得到充分解决。这项实验研究的目的是1)测试负重锻炼计划对青春期女性骨骼质量增加的影响；2)比较负重锻炼计划与负重锻炼计划和高钙饮食对青春期女性骨骼质量增加的影响。要检验的主要假设是：1)完成负重锻炼计划的青春期女性将比保持正常活动水平的青春期女性具有更高的脊柱BMC和跟骨SOS，以及2)完成负重锻炼计划和每天1500毫克高钙饮食干预的青春期女性将比完成锻炼计划但保持正常钙摄入量的青春期女性具有更高的脊椎BMC和跟骨SOS。我们将对107名年龄在10-13岁的女性进行另外四年半的跟踪调查。他们被随机分配到三组中的一组：1)每周3次负重锻炼计划的患者(当前n=35)；2)每周3次负重锻炼计划的患者，每天摄入高钙食物1500 mg(当前n=35)；或3)对照组，按常规饮食并维持他们的惯常活动水平(当前n=37)。每半年和研究结束时，将对所有参与者进行脊柱、髋关节、桡骨和全身BMC、跟骨SOS、身高、体重、Tanner分期以及病史和社会史的测量。通常的饮食摄入量和体力活动将每三个月进行一次评估，并在研究结束时进行。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，它们将有力地支持除了锻炼之外，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.