Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, UK.
Med Sci Sports Exerc. 2013 Sep;45(9):1749-58. doi: 10.1249/MSS.0b013e31828f882f.
The study of tennis players allows the nonracket arm to act as an internal control for the exercising racket arm. In addition, the study of the upper limbs removes the influence of gravitational loading, allowing the examination of the influence of muscular force on bone adaptation.
The role of muscular action on bone, strength parameters of the radius, ulna (both at 4% and 60% distal-proximal ulnar length), and humerus (at 35% distal-proximal humerus length) as well as muscle size in both arms of 50 elite junior tennis players (mean ± SD age = 13.5 ± 1.9 yr) were measured with peripheral quantitative computed tomography (pQCT).
Strong relationships were found between muscle size and bone size in both arms (all correlations, P < 0.001, R = 0.73-0.86). However, the muscle-bone ratio was significantly lower (P < 0.001) in the upper arm on the racket side (compared with the contralateral arm). In addition, material eccentricity analysis revealed that bone strength in bending and torsion increased more than strength in compression as the moment arms for these actions (bone length and width, respectively) increased (in all cases, P > 0.001, R = 0.06-0.7) with relationships being stronger in torsion than in bending. Large side differences were found in bone strength parameters and muscle size in all investigated sites, with differences in distal radius total BMC (+37% ± 21%) and humerus cortical cross-sectional area (+40% ± 12%) being most pronounced (both P < 0.001).
These results support a strong influence of muscular action on bone adaptation; however, interarm muscle-bone asymmetries suggest factors other than local muscle size that determine bone strength. The results also suggest that torsional loads provide the greatest stress experienced by the bone during a tennis stroke.
研究网球运动员可以使非球拍手臂作为运动球拍手臂的内部对照。此外，研究上肢可以消除重力负荷的影响，从而可以检查肌肉力量对骨骼适应的影响。
使用外周定量计算机断层扫描（pQCT）测量 50 名精英青少年网球运动员（平均±SD 年龄= 13.5±1.9 岁）的四肢肌肉作用、桡骨（在 4%和 60%的远端-近端尺骨长度处）和尺骨（在 35%的远端-近端尺骨长度处）的强度参数以及两支手臂的肌肉大小。
在两支手臂中均发现肌肉大小与骨骼大小之间存在很强的相关性（所有相关性，P<0.001，R=0.73-0.86）。但是，在球拍侧的上臂（与对侧手臂相比），肌肉-骨骼比明显较低（P<0.001）。此外，材料偏心率分析表明，随着这些动作的力臂（分别为骨骼长度和宽度）增加，弯曲和扭转的骨强度增加超过压缩强度（在所有情况下，P>0.001，R=0.06-0.7），扭转的关系强于弯曲。在所有研究部位均发现骨强度参数和肌肉大小的较大侧差异，其中桡骨远端总 BMC（增加 37%±21%）和肱骨皮质横截面积（增加 40%±12%）的差异最为明显（均 P<0.001）。
这些结果支持肌肉作用对骨骼适应的强烈影响；但是，手臂之间的肌肉骨骼不对称性表明，除了局部肌肉大小之外，还有其他因素决定骨强度。结果还表明，扭转负荷在网球击球过程中为骨骼提供了最大的应力。
