Does the mechanical milieu associated with high-speed running lead to adaptive changes in diaphyseal growing bone?
Does the mechanical milieu associated with high-speed running lead to adaptive changes in diaphyseal growing bone?
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DOI：
10.1016/s8756-3282(99)00256-2
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发表时间：
2000-02-01
期刊：
影响因子：
4.1
通讯作者：
Zernicke, RF
中科院分区：
文献类型：
--
作者：
Judex, S;Zernicke, RF
生长期间的锻炼对于获得最佳骨量很重要。然而，高强度长时间方案可能对未成熟骨形态和力学产生不利影响。其基本机制尚不清楚。在这里，我们量化的机械环境中的middiaphyseal公鸡tarsomatarsus在高速运行，并检查是否短回合的这种运动相关的机械环境可以诱导皮质骨形态，力学和矿物灰分含量的积极变化。在9周龄时，公鸡被分配到对照组（n = 9）和跑者组（n = 8），在跑步机上跑步，每天3次（约2600个周期/天），每次5分钟，持续8周。在方案的第3周和第8周期间，对照组和跑者都接受双荧光染料标记。通过在体应变仪测定了跗跖骨纵向正应变、应变率和步行和跑步产生的应变梯度的骨干分布。与步行相比，跑步使平均峰值应变幅度增加19%，峰值应变率增加136%，峰值应变梯度增加约18%。经过8周的运行，中间骨干面积和机械性能和归一化灰重之间的跑步者和对照组没有差异。在运动过程中，骨膜矿物质沉积率发生了短暂性和局灶性降低。我们目前的数据表明，减少负荷循环次数可以减轻先前在该模型中观察到的长时间跑步的不良反应。本研究还支持运动产生的机械环境必须与习惯环境有很大不同以诱导显著适应的原则。(C)2000年，Elsevier Science Inc. All rights reserved.
Exercise during growth can be important for attaining optimal bone mass. High-intensity long-duration protocols, however, can have detrimental effects on immature bone morphology and mechanics. The underlying mechanisms are poorly understood. Here, we quantified the mechanical environment of the middiaphyseal rooster tarsometatarsus during high-speed running and examined whether short bouts of this exercise-related mechanical milieu can induce positive changes in cortical bone morphology, mechanics, and mineral ash content. At 9 weeks of age, roosters were assigned to controls (n = 9) and runners (n = 8), Treadmill running was applied in loading sessions of 5 min, three times per day (approximate to 2600 cycles/day) for 8 weeks, Both controls and runners received double-fluorochrome labels during weeks 3 and 8 of the protocol. Middiaphyseal distributions of tarsometatarsal longitudinal normal strain, strain rate, and strain gradients engendered by walking and running were determined via in vivo strain gauges. Compared with walking, running elevated mean peak strain magnitude by 19%, peak strain rates by 136%, and peak strain gradients by approximately 18%. After 8 weeks of running, middiaphyseal areal and mechanical properties and normalized ash weight were no different between runners and controls. Transient and focal reductions in periosteal mineral apposition rates occurred during the exercise protocol, Our current data suggest that reducing the number of loading cycles can mitigate the adverse response previously observed in this model with long-duration running, This study also supports the tenet that the exercise-generated mechanical milieu must differ substantially from the habitual milieu to induce significant adaptations. (C) 2000 by Elsevier Science Inc. All rights reserved.