LOADING EXERCISE PROGRAMS AND BONE GAIN IN YOUNG WOMEN

成人骨量和密度部分取决于峰值骨量 在生命的第二个十年结束时实现的目标和 骨量可能占老年人骨量变异性的一半 人士 低髋骨密度是髋骨骨折的一个强有力的预测因素。 因此，老年人骨折的风险在很大程度上是早期确定的 生活中 峰值骨量的主要决定因素似乎是 遗传、性别、年龄、青少年荷尔蒙状态、钙营养和 体力活动。 其中，只有营养和体力活动是 可修饰的决定因素，我们的研究小组先前已经表明， 青少年妇女的补充不能有效地实现 骨质的永久性增加。 的长远目标， 拟议的研究是为了帮助理解的作用， 锻炼对青春期女孩骨骼发育的影响。 我们将 检查两种运动干预的效果， 少量高作用力和高加载速率冲击或大量 低力和低加载速率冲击的次数较低 四肢 对照组将进行不涉及 额外的下肢负荷。 在这方面设计的干预措施 根据初步研究和骨重建理论， 10分钟的表演，每周进行三次， 为期两个36周的学年，作为 中学体育课。 下肢负荷 将使用计算机化的 力监测器和加速度计估计的数量和大小 也将产生影响。 我们假设十分钟的 每周进行三次高力量/高负荷率运动， 36周的时间将对骨增量产生显著影响， 久坐不动的青春期女孩，但将显示很少或没有影响， 姑娘们 也可能的是，10分钟的低力/低负载 在相同的时间内进行的利率演习可能有显着的 影响久坐或活跃的青春期女孩的骨增量。 的 载荷测量结果也将使目前的骨骼理论 在这个重要的年龄组中进行定量测试。 一 拟议研究的积极成果可能会引起公众的广泛关注。 健康影响，因为拟议的干预措施很容易 在全国公立学校实施。

Adult bone mass and density depend, in part, upon peak bone mass achieved by the end of the second decade of life and differences in peak bone mass may account for half the variability in bone mass in elderly persons. Low hip bone density is a strong predictor of hip fractures. Thus, the risk of fracture in the elderly is largely determined early in life. The major determinants of peak bone mass appear to be heredity, gender, age, adolescent hormonal status, calcium nutrition and physical activity. Of these, only nutrition and physical activity are modifiable determinants and our group has previously shown that calcium supplementation in adolescent women is not effective in achieving permanent gains in bone mass. The broad long term objective of the proposed research is to contribute to an understanding of the role of exercise in the acquisition of bone in adolescent girls. We will examine the effect of two exercise interventions involving either a small number of high force and high loading rate impacts or a large number of low force and low loading rate impacts to the lower extremities. A control group will perform exercises involving no additional lower extremity loading. The interventions designed on the basis of pilot studies and bone remodeling theories, will take less than 10 minutes to perform and will be conducted three times per week for a duration of two 36 week school years as part of the warm-up period in middle school physical education classes. Lower extremity loading throughout entire days will be directly measured using a computerized force monitor and accelerometer estimates of the number and magnitude of impacts will also be obtained. We hypothesize that ten minutes of high force/high loading rate exercise conducted three times a week for a period of 36 weeks will have a significant effect on bone gain in sedentary adolescent girls but will show little or no effect in active girls. It is also possible that ten minutes of low force/low loading rate exercise conducted for the same duration may have significant effect on bone gain in either sedentary or active adolescent girls. The load measurement results will also allow current theories of bone remodeling to be quantitatively tested in this important age group. A positive outcome from the proposed study could have a significant public health impact since the proposed intervention could be easily implemented in public schools nationwide.