Force-velocity and force-power properties of single muscle fibers from elite master runners and sedentary men.
Force-velocity and force-power properties of single muscle fibers from elite master runners and sedentary men.
复制标题
精英跑步大师和久坐男子的单肌纤维的力-速度和力-功率特性。
DOI：
10.1152/ajpcell.1996.271.2.c676
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Fitts,RH
中科院分区：
文献类型：
--
作者：
Widrick,JJ;Trappe,SW;Costill,DL;Fitts,RH
腓肠肌肌纤维束通过针吸活检从5名中年久坐男性（SED组）和6名年龄匹配的耐力训练的跑步大师（RUN组）获得。将单个化学透化的纤维段安装在力传感器和位置马达之间，在最大Ca 2+活化（15 ° C）下进行一系列等张收缩，随后在5%聚丙烯酰胺凝胶上运行以确定肌球蛋白重链组成。将Hill方程拟合到针对每种单独纤维获得的数据（r2 >或= 0.98）。对于SED组，纤维力-速度参数变化（P < 0.05）肌球蛋白重链表达情况如下：峰值力，无差异：峰值张力（力/纤维横截面积），IIx型> IIa型> I型;最大缩短速度（Vmax，定义为力-速度关系的y轴截距），IIx型= IIa型> I型; a/Pzero（其中a是力的量纲的常数，Pzero是峰值等距力），类型IIx >类型IIa >类型I。因此，IIx型光纤产生的峰值功率是IIa型光纤的两倍，而IIa型光纤产生的峰值功率是I型光纤的五倍。RUN I型和IIa型纤维的直径较小，产生的峰值力也低于SED I型和IIa型纤维。RUN I型和IIa型光纤的绝对峰值功率输出分别比类似类型的SED光纤的峰值功率小13%和27%。然而，SED组和RUN组之间的I型和IIa型Vmax和a/Pzero没有差异，并且在针对纤维直径差异进行功率标准化后，RUN I型和IIa型功率不足消失。因此，来自主转轮的I型和IIa型纤维的降低的绝对峰值功率输出是这些纤维的较小直径和它们的峰值等长力产生的相应降低的结果。在单纤维水平的绝对峰值功率产生的这种损害可能是部分负责减少体内功率输出先前观察到的耐力训练的运动员。
Gastrocnemius muscle fiber bundles were obtained by needle biopsy from five middle-aged sedentary men (SED group) and six age-matched endurance-trained master runners (RUN group). A single chemically permeabilized fiber segment was mounted between a force transducer and a position motor, subjected to a series of isotonic contractions at maximal Ca2+ activation (15 degrees C), and subsequently run on a 5% polyacrylamide gel to determine myosin heavy chain composition. The Hill equation was fit to the data obtained for each individual fiber (r2 > or = 0.98). For the SED group, fiber force-velocity parameters varied (P < 0.05) with fiber myosin heavy chain expression as follows: peak force, no differences: peak tension (force/fiber cross-sectional area), type IIx > type IIa > type I; maximal shortening velocity (Vmax, defined as y-intercept of force-velocity relationship), type IIx = type IIa > type I; a/Pzero (where a is a constant with dimensions of force and Pzero is peak isometric force), type IIx > type IIa > type I. Consequently, type IIx fibers produced twice as much peak power as type IIa fibers, whereas type IIa fibers produced about five times more peak power than type I fibers. RUN type I and IIa fibers were smaller in diameter and produced less peak force than SED type I and IIa fibers. The absolute peak power output of RUN type I and IIa fibers was 13 and 27% less, respectively, than peak power of similarly typed SED fibers. However, type I and IIa Vmax and a/Pzero were not different between the SED and RUN groups, and RUN type I and IIa power deficits disappeared after power was normalized for differences in fiber diameter. Thus the reduced absolute peak power output of the type I and IIa fibers from the master runners was a result of the smaller diameter of these fibers and a corresponding reduction in their peak isometric force production. This impairment in absolute peak power production at the single fiber level may be in part responsible for the reduced in vivo power output previously observed for endurance-trained athletes.