Maughan R J, Nimmo M A
J Physiol. 1984 Jun;351:299-311. doi: 10.1113/jphysiol.1984.sp015246.
The force produced by a maximum voluntary isometric contraction of the knee-extensor muscles was measured in a group of fifteen healthy young male volunteers. All subjects were untrained at the time of the study. The cross-sectional area of the knee-extensor muscles was measured at the mid-thigh level using computed tomography. Skeletal muscle samples were obtained by needle biopsy from the mid-point of m. vastus lateralis of the stronger leg of each subject. Samples were mounted, frozen and sectioned for histochemical analysis. On the basis of the pH dependent lability of the myosin ATP-ase reaction, fibres were classified as Type I, Type IIA or Type II B. Using computerized planimetry, muscle fibre cross-sectional areas were measured on serial sections stained for succinate dehydrogenase activity. As previously described, muscle strength (maximum voluntary contraction) was correlated with the muscle cross-sectional area (r = 0.70, P less than 0.01). The ratio of strength (in N) to cross-sectional area (in cm2) was 8.92 +/- 1.01 (mean +/- S.D.) with a wide range of values, from 7.09 to 10.85. Muscle fibre composition of m. vastus lateralis in these subjects was 46.1 +/- 10.5% Type I, 42.8 +/- 11.4% Type IIA and 11.1 +/- 9.7% Type IIB. After correction for differences in the cross-sectional areas of the different fibre types, the proportions of total area occupied by the different fibre types were: 43.6 +/- 11.9% Type I, 46.4 +/- 13.1% Type IIA and 10.0 +/- 9.1% Type IIB. No relationship was observed to exist between muscle strength and muscle fibre composition. Similarly, the muscle strength/cross-sectional area ratio was not related to the proportions of the different fibre types present or to the fraction of the total cross-sectional area occupied by the different fibre types. From the results it can be concluded that there is no difference in the force per unit area which can be generated by the different muscle fibre types present in human skeletal muscle. Variations in muscle fibre composition between individuals cannot, therefore, account for the large variations observed in the ratio of strength to muscle cross-sectional area.
在一组15名健康年轻男性志愿者中，测量了膝伸肌最大自主等长收缩产生的力量。在研究时，所有受试者均未经过训练。使用计算机断层扫描在大腿中部水平测量膝伸肌的横截面积。通过针吸活检从每个受试者较强壮腿部的股外侧肌中点获取骨骼肌样本。样本被固定、冷冻并切片用于组织化学分析。根据肌球蛋白ATP酶反应的pH依赖性不稳定性，纤维被分类为I型、IIA型或IIB型。使用计算机化平面测量法，在琥珀酸脱氢酶活性染色的连续切片上测量肌纤维横截面积。如前所述，肌肉力量（最大自主收缩）与肌肉横截面积相关（r = 0.70，P小于0.01）。力量（以牛顿为单位）与横截面积（以平方厘米为单位）的比值为8.92±1.01（平均值±标准差），取值范围广泛，从7.09到10.85。这些受试者股外侧肌的肌纤维组成是46.1±10.5%的I型、42.8±11.4%的IIA型和11.1±9.7%的IIB型。在对不同纤维类型的横截面积差异进行校正后，不同纤维类型所占总面积的比例为：43.6±11.9%的I型、46.4±13.1%的IIA型和10.0±9.1%的IIB型。未观察到肌肉力量与肌纤维组成之间存在关系。同样，肌肉力量/横截面积比值与不同纤维类型的比例或不同纤维类型所占总横截面积的比例无关。从结果可以得出结论，人类骨骼肌中存在的不同肌纤维类型每单位面积产生的力量没有差异。因此，个体之间肌纤维组成的差异不能解释在力量与肌肉横截面积比值中观察到的巨大差异。
