EFFECT OF EXERCISE ON BONE MODELING DURING GROWTH

描述：(改编自调查员摘要)调查员的 目的是开发和使用非侵入性方法来评估：(1) 体育锻炼对骨骼发育和成熟的影响；及(2) 将这些变化与骨骼肌和肌肉的相关变化联系起来 他们的肌腱。他们将检查表型可塑性的程度 脊椎动物肌肉骨骼系统的综合反应 锻炼身体。这些动物实验将有助于增加对 所有动物共有的肌肉骨骼系统的设计原则， 包括人类在内，在康复和康复方面将有潜在的应用 与体力活动相关的对儿童和成人的训练。 研究人员将使用的模型包括对骨骼的 按功能等值记录体内应变的加载历史 在运动期间的特定时间，骨骼上的部位。 相应地，肌肉及其肌腱的负荷历史是 使用力-平台/运动学分析确定并直接在体内进行 肌腱受力记录。运动是不同的，通过让动物在 跑步机以不同的速度和持续时间，并通过改变负荷 这些动物背在背上。加载历史的已知参数 对于骨骼、肌肉和肌腱，则可以与量化的变化相关 在形态上，重点是骨形成和吸收率 组织的应变历史已知的地点。具体地说， 将检验以下三个假设：(1)骨骼模型 在功能相同的部位保持均匀的应变分布； (2)破坏了应变的正态分布，而不是 高应变本身是诱导适应性骨的最关键的因素 模型；(3)骨骼、肌肉和肌腱的质量和形态 动物的四肢相匹配，以保持与失败相似的安全系数， 提供一体化设计，以防止受伤或故障。为了测试 在这些假设下，研究人员将量化骨骼、肌肉和肌腱 在成长雏鸡和仓鼠的跑步机运动中的负荷。匹配的 实验将在成熟的动物身上进行，以比较适应性 成熟骨、肌肉和肌腱的成熟期和成长期的可塑性。他们会 此外，更准确地评估正常生活的中断程度 骨骼皮质的应变梯度影响自适应建模反应 在骨头上。

DESCRIPTION: (Adapted from investigator's abstract) The investigator's objective is to develop and use non-invasive approaches to evaluate: (1) the effect of physical exercise on the growing and mature skeleton; and (2) to relate these changes to correlated changes in the skeletal muscles and their tendons. They will examine the extent to which phenotypic plasticity of the vertebrate musculoskeletal system in an integrated response to exercise. These animal experiments will help increase the understanding of the design principles of the musculoskeletal system common to all animals, including humans, and will have potential application in rehabilitation and training of children and adults associated with physical activity. The model the investigators will use involves quantification of the bone's loading history by recording in vivo strain at functionally equivalent sites on the bone at specific time during the exercise period. Correspondingly, the loading history of the muscles and their tendons are determined using force-platform/kinematic analyses and direct in vivo tendon force recordings. Exercise is varied by running the animals on a treadmill at different speeds and duration, and by varying the loads that the animals carry on their backs. Known parameters of the loading history for the bone, muscles and tendons can then be related to quantified changes in their morphology, focusing on bone formation and resorption rates at sites where the tissues's strain history is known. Specifically, the following three hypotheses will be tested: (1) that bone models to maintain a uniform distribution of strain at functionally equivalent sites; (2) that disruption of the normal distribution of strain, rather than elevated strain per se, is most critical for eliciting adaptive bone modeling; and (3) that the mass and form of bone, muscle and tendon in an animals's limb is matched to maintain a similar safety factor to failure, providing integrated design to protect against injury or failure. To test these hypotheses, the investigators will quantify bone, muscle and tendon loading during treadmill exercise in growing chicks and hamsters. Matched experiments will be carried out on mature animals to compare the adaptive plasticity of mature versus growing bone, muscle and tendon. They will also, evaluate more precisely the extent to which disruption of normal strain gradients in the bone's cortex affects adaptive modeling responses of the bone.