Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, VIC 3125, Australia.
J Clin Endocrinol Metab. 2013 May;98(5):2037-44. doi: 10.1210/jc.2012-3748. Epub 2013 Apr 24.
Increased mechanical loading can promote the preferential differentiation of bone marrow mesenchymal stem cells to osteoblastogenesis, but it is not known whether long-term bone strength-enhancing exercise in humans can reduce marrow adiposity.
Our objective was to examine whether bone marrow density (MaD), as an estimate of marrow adiposity 1) differs between young female athletes with contrasting loading histories and bone strengths and 2) is an independent predictor of bone strength at the weight-bearing tibia.
Mid-tibial MaD, cortical area (CoA), total area, medullary area, strength strain index (SSI), and cortical volumetric bone mineral density (vBMD) (total, endocortical, midcortical, and pericortical) was assessed using peripheral quantitative computed tomography in 179 female athletes involved in both impact and nonimpact loading sports and 41 controls aged 17-40 years.
As we have previously reported CoA, total area, and SSI were 16% to 24% greater in the impact group compared with the controls (all P < .001) and 12% to 18% greater than in the nonimpact group (all P < .001). The impact group also had 0.5% higher MaD than the nonimpact and control groups (both P < .05). Regression analysis further showed that midtibial MaD was significantly associated with SSI, CoA, endocortical vBMD, and pericortical vBMD (P < .05) in all women combined, after adjusting for age, bone length, loading groups, medullary area, muscle cross-sectional area, and percent fat.
In young female athletes, tibial bone MaD was associated with loading history and was an independent predictor of tibial bone strength. These findings suggest that an exercise-induced increase in bone strength may be mediated via reduced bone marrow adiposity and consequently increased osteoblastogenesis.
增加机械负荷可以促进骨髓间充质干细胞向成骨细胞的优先分化，但目前尚不清楚人类长期增强骨骼力量的运动是否可以减少骨髓脂肪含量。
我们的目的是研究年轻女性运动员中，1）不同负荷史和骨强度的运动员骨髓密度（MaD）是否存在差异，2）MaD 是否是承重胫骨骨强度的独立预测因子。
使用外周定量计算机断层扫描评估 179 名从事冲击和非冲击负荷运动的女性运动员和 41 名年龄在 17-40 岁之间的对照组的胫骨中部 MaD、皮质区（CoA）、总面积、髓腔面积、强度应变指数（SSI）和皮质体积骨矿物质密度（vBMD）（总、内皮质、中皮质和皮质旁）。
正如我们之前报道的，与对照组相比，冲击组的 CoA、总面积和 SSI 分别增加了 16%至 24%（均 P <.001），比非冲击组增加了 12%至 18%（均 P <.001）。冲击组的 MaD 也比非冲击组和对照组高 0.5%（均 P <.05）。回归分析进一步表明，调整年龄、骨长、负荷组、髓腔面积、肌肉横截面积和脂肪百分比后，所有女性的胫骨中部 MaD 与 SSI、CoA、内皮质 vBMD 和皮质旁 vBMD 显著相关（均 P <.05）。
在年轻女性运动员中，胫骨骨 MaD 与负荷史有关，是胫骨骨强度的独立预测因子。这些发现表明，运动引起的骨强度增加可能是通过减少骨髓脂肪含量和增加成骨细胞形成来介导的。
