Mustafy Tanvir, Londono Irène, Moldovan Florina, Villemure Isabelle
Department of Mechanical Engineering École Polytechnique of Montréal Montréal Québec Canada.
Department of Pediatrics Sainte-Justine University Hospital Center Montréal Québec Canada.
JBMR Plus. 2020 Mar 11;4(4):e10349. doi: 10.1002/jbm4.10349. eCollection 2020 Apr.
Bone is a unique living tissue, which responds to the mechanical stimuli regularly imposed on it. Adolescence facilitates a favorable condition for the skeleton that enables the exercise to positively influence bone architecture and overall strength. However, it is still dubious for how long the skeletal benefits gained in adolescence is preserved at adulthood. The current study aims to use a rat model to investigate the effects of low- (LI), medium- (MI), and high- (HI) intensity cyclic loadings applied during puberty on longitudinal bone development, morphometry, and biomechanics during adolescence as well as at adulthood. Forty-two young (4-week-old) male rats were randomized into control, sham, LI, MI, and HI groups. After a 5 day/week for 8 weeks cyclic loading regime applied on the right tibia, loaded rats underwent a subsequent 41-week, normal cage activity period. Right tibias were removed at 52 weeks of age, and a comprehensive assessment was performed using μCT, mechanical testing, and finite element analysis. HI and MI groups exhibited reduced body weight and food intake at the end of the loading period compared with shams, but these effects disappeared afterward. HI cyclic loading increased BMD, bone volume fraction, trabecular thickness, trabecular number, and decreased trabecular spacing after loading. All loading-induced benefits, except BMD, persisted until the end of the normal cage activity period. Moreover, HI loading induced enhanced bone area, periosteal perimeter, and moment of inertia, which remained up to the 52nd week. After the normal cage activity at adulthood, the HI group showed increased ultimate force and stress, stiffness, postyield displacement and energy, and toughness compared with the sham group. Overall, our findings suggest that even though both trabecular and cortical bone drifted through age-related changes during aging, HI cyclic loading performed during adolescence can render lifelong benefits in bone microstructure and biomechanics. © 2020 The Authors. published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
骨骼是一种独特的活体组织，它会对经常施加于其上的机械刺激作出反应。青春期为骨骼创造了有利条件，使运动能够对骨骼结构和整体强度产生积极影响。然而，青春期获得的骨骼益处能在成年期保留多长时间仍不明确。当前的研究旨在使用大鼠模型，研究青春期施加的低强度（LI）、中等强度（MI）和高强度（HI）循环负荷对青春期以及成年期骨骼纵向发育、形态测量和生物力学的影响。42只年轻（4周龄）雄性大鼠被随机分为对照组、假手术组、LI组、MI组和HI组。在对右侧胫骨施加每周5天、持续8周的循环负荷方案后，接受负荷的大鼠进入随后41周的正常笼内活动期。在52周龄时取出右侧胫骨，并使用μCT、力学测试和有限元分析进行全面评估。与假手术组相比，HI组和MI组在负荷期结束时体重和食物摄入量减少，但这些影响随后消失。HI循环负荷增加了负荷后骨密度、骨体积分数、小梁厚度、小梁数量，并减小了小梁间距。除骨密度外，所有负荷诱导的益处一直持续到正常笼内活动期结束。此外，HI负荷增加了骨面积、骨膜周长和惯性矩，这些增加一直持续到第52周。成年期正常笼内活动后，与假手术组相比，HI组的极限力、应力、刚度、屈服后位移和能量以及韧性增加。总体而言，我们的研究结果表明，尽管在衰老过程中松质骨和皮质骨都会因年龄相关变化而发生改变，但青春期进行的HI循环负荷可在骨骼微观结构和生物力学方面带来终身益处。© 2020作者。由Wiley Periodicals, Inc.代表美国骨与矿物质研究学会出版。
