Although strong evidence exists that certain activities can increase bone density and structure in people, it is unclear what specific mechanical factors govern the response. This is important because understanding the effect of mechanical signals on bone could contribute to more effective osteoporosis prevention methods and efficient clinical trial design. The degree to which strain rate and magnitude govern bone adaptation in humans has never been prospectively tested. Here, we studied the effects of a voluntary upper extremity compressive loading task in healthy adult women during a 12‐month prospective period. A total of 102 women age 21 to 40 years participated in one of two experiments: (i) low (n = 21) and high (n = 24) strain magnitude; or (ii) low (n = 21) and high (n = 20) strain rate. Control (n = 16) no intervention. Strains were assigned using subject‐specific finite element models. Load cycles were recorded digitally. The primary outcome was change in ultradistal radius integral bone mineral content (iBMC), assessed with QCT. Interim time points and secondary outcomes were assessed with high resolution pQCT (HRpQCT) at the distal radius. Sixty‐six participants completed the intervention, and interim data were analyzed for 77 participants. Likely related to improved compliance and higher received loading dose, both the low‐strain rate and high‐strain rate groups had significant 12‐month increases to ultradistal iBMC (change in control: −1.3 ± 2.7%, low strain rate: 2.7 ± 2.1%, high strain rate: 3.4 ± 2.2%), total iBMC, and other measures. “Loading dose” was positively related to 12‐month change in ultradistal iBMC, and interim changes to total BMD, cortical thickness, and inner trabecular BMD. Participants who gained the most bone completed, on average, 128 loading bouts of (mean strain) 575 με at 1878 με/s. We conclude that signals related to strain magnitude, rate, and number of loading bouts contribute to bone adaptation in healthy adult women, but only explain a small amount of variance in bone changes. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

中文翻译：

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成年女性的骨骼适应与负荷剂量有关：一项为期 12 个月的随机对照试验。

尽管有强有力的证据表明某些活动可以增加人的骨密度和结构，但尚不清楚哪些特定的机械因素控制着这种反应。这很重要，因为了解机械信号对骨骼的影响可能有助于更有效的骨质疏松症预防方法和有效的临床试验设计。从未对应变率和大小控制人类骨骼适应的程度进行前瞻性测试。在这里，我们研究了在 12 个月的预期期内，自愿上肢压缩负荷任务对健康成年女性的影响。共有 102 名 21 至 40 岁的女性参加了以下两个实验之一：(i) 低 ( n = 21) 和高 ( n = 24) 应变幅度；或 (ii) 低 ( n= 21) 和高 ( n = 20) 应变率。控制 ( n= 16) 没有干预。使用特定主题的有限元模型分配应变。负载循环以数字方式记录。主要结果是使用 QCT 评估的桡骨远端骨矿物质含量 (iBMC) 的变化。在桡骨远端使用高分辨率 pQCT (HRpQCT) 评估中期时间点和次要结果。66 名参与者完成了干预，并对 77 名参与者的中期数据进行了分析。可能与改善的顺应性和更高的负荷剂量有关，低应变率和高应变率组的超远端 iBMC 均在 12 个月内显着增加（控制变化：-1.3 ± 2.7%，低应变率：2.7 ± 2.1 %，高应变率：3.4 ± 2.2%），总 iBMC 和其他措施。“负荷剂量”与超远端 iBMC 的 12 个月变化呈正相关，总骨密度、皮质厚度和内小梁骨密度的临时变化。获得最多骨骼的参与者平均以 1878 με/s 完成 128 次（平均应变）575 με 的加载回合。我们得出结论，与应变幅度、速率和加载次数相关的信号有助于健康成年女性的骨骼适应，但只能解释骨骼变化的少量差异。© 2020 作者。美国骨与矿物质研究学会出版的骨与矿物质研究杂志。