The effect of mechanical loading on the size and shape of bone in pre-, peri-, and postpubertal girls: A study in tennis players
The effect of mechanical loading on the size and shape of bone in pre-, peri-, and postpubertal girls: A study in tennis players
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DOI：
10.1359/jbmr.2002.17.12.2274
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发表时间：
2002-12-01
影响因子：
6.2
通讯作者：
Stuckey, S
中科院分区：
文献类型：
--
作者：
Bass, SL;Saxon, L;Stuckey, S
生长期间的运动导致骨矿物质含量（BMC）的生物学上重要的增加。本研究的目的是确定加载的影响是否具有站点特异性，并取决于该地区的成熟阶段。采用DXA和磁共振成像（MRI）对47名8-17岁的竞技女子网球运动员负重和非负重臂的BMC和肱骨尺寸进行了测定。计算负重臂和非负重臂中远端骨膜（外）横截面积（CSA）、皮质面积、髓质面积和极秒矩面积（I-P mm(4)）。在青春期前运动员中，负重组的BMC和I-P比未负重组高11-14%，而在青春期前后运动员中，尽管负重时间较长，但BMC和I-P没有进一步增加（均p < 0.01）。由于肱骨中部骨膜扩张大于髓质扩张，且肱骨远端骨膜扩张大于髓质扩张，因此，青春期前运动员的BMC较高，其皮质面积增加了7-11%。青春期晚期的负荷导致髓质收缩。生长和负荷的影响是区域和表面特异性的，青春期前的骨膜附着增加了骨骼对扭转的抵抗力，而青春期后期的皮质内收缩增加了对扭转的抵抗力。增加骨的抗扭转能力是通过改变骨的形状和质量来实现的，而不一定是骨密度。
Exercise during growth results in biologically important increases in bone mineral content (BMC). The aim of this study was to determine whether the effects of loading were site specific and depended on the maturational stage of the region. BMC and humeral dimensions were determined using DXA and magnetic resonance imaging (MRI) of the loaded and nonloaded arms in 47 competitive female tennis players aged 8-17 years. Periosteal (external) cross-sectional area (CSA), cortical area, medullary area, and the polar second moments of area (I-P mm(4)) were calculated at the mid and distal sites in the loaded and nonloaded arms. BMC and I-P of the humerus were 11-14% greater in the loaded arm than in the nonloaded arm in prepubertal players and did not increase further in peri- or postpubertal players despite longer duration of loading (both, p < 0.01). The higher BMC was the result of a 7-11% greater cortical area in the prepubertal players due to greater periosteal than medullary expansion at the midhumerus and a greater periosteal expansion alone at the distal humerus. Loading late in puberty resulted in medullary contraction. Growth and the effects of loading are region and surface specific, with periosteal apposition before puberty accounting for the increase in the bone's resistance to torsion and endocortical contraction contributing late in puberty conferring little increase in resistance to torsion. Increasing the bone's resistance to torsion is achieved by modifying bone shape and mass, not necessarily bone density.