Relationship between force and size in human single muscle fibres
Relationship between force and size in human single muscle fibres
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DOI：
10.1113/expphysiol.2010.055269
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发表时间：
2011-05-01
影响因子：
2.7
通讯作者：
Frontera, Walter R.
中科院分区：
文献类型：
--
作者：
Krivickas, Lisa S.;Dorer, David J.;Frontera, Walter R.
当研究单个肌纤维的收缩特性时，力通常通过纤维横截面积归一化并表示为比力。我们研究了来自119名健康成年人的2725根化学去皮的人类单根肌纤维，以确定比力是否是表达单根纤维力与尺寸之间关系的最佳方式。线性混合效应模型被用来估计的斜率和斜率变异个体的双对数图的力和直径。对于I型纤维，斜率估计值为0.99（95%置信区间0.36-1.62），对于IIa型纤维，斜率估计值为0.94（95%置信区间0.77-1.11），表明力与纤维直径成比例，而不是与横截面积成比例。如果力与横截面积成比例，则斜率估计值为2.0。在未来的研究中，使用化学结皮的单纤维制备，力可能会被归一化为纤维直径，而不是横截面积。我们建议用一个新的术语“归一化力”来表示这个变量，单位为牛顿每米。我们证明使用我们的数据集，当人口的单纤维相互比较，大小和力的关系是否相同或不同的确定是取决于用于占纤维大小的方法（即比力与“归一化力”）。
When the contractile properties of single muscle fibres are studied, force is typically normalized by fibre cross-sectional area and expressed as specific force. We studied a set of 2725 chemically skinned human single muscle fibres from 119 healthy adults to determine whether specific force is the optimal way to express the relationship between single-fibre force and size. A linear mixed effects model was used to estimate the slope and slope variability among individuals of log-log plots of force and diameter. For type I fibres, the slope estimate was 0.99 (95% confidence interval 0.36-1.62), and for type IIa fibres it was 0.94 (95% confidence interval 0.77-1.11), indicating that force is proportional to fibre diameter, rather than to cross-sectional area. If force were proportional to cross-sectional area, the slope estimate would be 2.0. In future studies using the chemically skinned single fibre preparation, force may be normalized to fibre diameter rather than cross-sectional area. We propose that a new term, 'normalized force', be used for this variable, with units of newtons per metre. We demonstrate using our data set that when populations of single fibres are compared with one another, the determination of whether the size and force relationship is the same or different is dependent upon the method used to account for fibre size (i.e. specific force versus 'normalized force').