GENUD (Growth, Exercise, NUtrition and Development) Research Group, Zaragoza, Spain.
Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Madrid, Spain.
Osteoporos Int. 2019 May;30(5):1079-1088. doi: 10.1007/s00198-019-04857-3. Epub 2019 Feb 7.
Most researchers adjust bone by lean mass when comparing swimmers with controls. This adjustment is done under the assumption that lean affects bone similarly in both groups. Nonetheless, we found that the muscle-bone association is uncoupled in swimmers, and consequently, researchers should avoid this adjustment when evaluating swimmers' bone.
To examine the functional and structural muscle-bone unit in adolescent swimmers.
Sixty-five swimmers (34 girls/31 boys) and 119 controls (51 girls/68 boys) participated in the study. Muscle cross-sectional area (MCSA), bone mineral content (BMC), and polar strength-strain index (SSIPOL) were measured in the non-dominant radius by peripheral quantitative computed tomography (pQCT). Subtotal BMC and lean mass were evaluated with dual-energy X-ray absorptiometry (DXA). Handgrip and isometric knee extension (IKE) tests were performed to determine muscle force. The effect of MCSA, lean and force on SSIPOL, and BMC were tested, and the functional and structural muscle-bone ratios of swimmers and controls were compared.
Both muscle size (MCSA and lean) and muscle force (handgrip and IKE) influenced BMC and SSIPOL in swimmers and controls similarly. Swimmers presented normal MCSA and lean values for their height, but when compared with controls, swimmers presented a higher amount of lean and MCSA for the same BMC or SSIPOL (structural muscle-bone unit). For the functional muscle-bone unit, different results were found for the lower and upper limbs, as no differences were found for the upper limbs, while for the lower limbs, swimmers presented higher muscle force for the same amount of BMC.
The contradictory results regarding BMC in swimmers found in previous studies could partly be explained with the findings of the present study that reinforce the idea that swimming is not an effective sport to practice regarding bone mass and that the muscle-bone unit is different in swimmers than in controls.
大多数研究人员在比较游泳运动员和对照组时，通过瘦体重调整骨量。这种调整是基于这样的假设，即瘦体重对两组的骨骼影响相似。然而，我们发现游泳运动员的肌肉-骨骼关联是解耦的，因此，研究人员在评估游泳运动员的骨骼时应避免这种调整。
研究青少年游泳运动员的功能性和结构性肌肉-骨骼单位。
本研究纳入了 65 名游泳运动员（34 名女性/31 名男性）和 119 名对照组（51 名女性/68 名男性）。通过外周定量计算机断层扫描（pQCT）测量非优势桡骨的肌肉横截面积（MCSA）、骨矿物质含量（BMC）和极强度应变指数（SSIPOL）。通过双能 X 射线吸收法（DXA）评估总 BMC 和瘦体重。进行握力和等长膝关节伸展（IKE）测试以确定肌肉力量。测试 MCSA、瘦体重和力量对 SSIPOL 和 BMC 的影响，并比较游泳运动员和对照组的功能性和结构性肌肉-骨骼比。
肌肉大小（MCSA 和瘦体重）和肌肉力量（握力和 IKE）对游泳运动员和对照组的 BMC 和 SSIPOL 均有影响。游泳运动员的 MCSA 和瘦体重与身高相匹配，但与对照组相比，游泳运动员的瘦体重和 MCSA相同，但 BMC 或 SSIPOL 更高（结构性肌肉-骨骼单位）。对于功能性肌肉-骨骼单位，上下肢的结果不同，上肢没有差异，而对于下肢，游泳运动员的 BMC 相同，但肌肉力量更高。
先前研究中关于游泳运动员 BMC 的矛盾结果部分可以用本研究的发现来解释，这进一步强调了游泳不是一种有效的增加骨量的运动，并且游泳运动员的肌肉-骨骼单位与对照组不同。
