Knee extensor torque and quadriceps femoris EMG during perceptually-guided isometric contractions
Knee extensor torque and quadriceps femoris EMG during perceptually-guided isometric contractions
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DOI：
10.1016/s1050-6411(02)00096-2
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发表时间：
2003-04-01
影响因子：
2.5
通讯作者：
Suter, E
中科院分区：
文献类型：
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作者：
Pincivero, DM;Coelho, AJ;Suter, E
本研究的目的是探讨股四头肌（QF）的表面肌电和扭矩知觉自愿收缩的努力。30名受试者（15名男性，15名女性）以随机顺序在11点量表（0-10）的1-9点进行9，5 s，次最大收缩。股内侧肌（VM）、股外侧肌（VL）和股直肌（RF）的表面肌电图（EMG），以及QF峰值扭矩（PT）、平均扭矩（AT）和扭矩变异系数（C. V.），被取样。对原始肌电信号进行全波整流，并在每次收缩的中间三s进行积分。采样的EMG信号，以及PT和AT在每个感知的用力水平被归一化为三个最大自主收缩的平均值。然后将每个感知用力水平下的标准化EMG和扭矩值与等效百分比值（即，10%，在1的感知水平）。结果表明，在所有感知的用力水平下，除了RF处于相当于20%的水平2，以及VL和RF肌肉处于激活大于10%的水平1外，激活显著小于量表上每个点的等效百分比值。从收缩水平3-9发现VM EMG小于VL和RF。在收缩水平为6-9时，PT显示为小于等效百分比值。AT被认为是低于预期的百分比值在感知的努力水平2-9。扭矩CV。在感知努力的范围内没有发现不同。这项研究的主要发现表明，人类高估自愿QF肌肉扭矩时，由知觉的感觉。它还表明，所产生的EMG信号揭示了在次最大水平的膝关节伸肌扭矩产生的VL肌肉的依赖。(C)2003爱思唯尔科技有限公司版权所有。
The aim of this study was to examine superficial quadriceps femoris (QF) EMG and torque at perceived voluntary contraction efforts. Thirty subjects (15 males, 15 females) performed 9, 5 s, sub-maximal contractions at prescribed levels of perceived voluntary effort at points 1-9 on an 11-point scale (0-10), in a random order. Surface electromyograms (EMG) of the vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF) muscles, as well as QF peak torque (PT), average torque (AT), and torque coefficient of variation (C.V.), were sampled. The raw EMG signals were full-wave rectified and integrated over the middle three s of each contraction. The sampled EMG signals, and PT and AT at each perceived exertion level were normalized to the average of three maximal voluntary contractions. The normalized EMG and torque values at each perceived exertion level were then compared to equivalent percent values (i.e., 10% at a perceived level of 1). The results demonstrated that at all perceived exertion levels, with the exception of the RF at a level of 2 which was equivalent to 20%, and the VL and RF muscles at a level 1 in which activation was greater than 10%, activation was significantly less than the equivalent percent value at each point on the scale. VM EMG was found to be less than the VL and RF from contraction levels 3-9. PT was shown to be less than the equivalent percent values at contraction levels 6-9. The AT was found to be lower than the expected percent value at perceived effort levels 2-9. Torque CV. was not found to be different across the range of perceived effort. The major findings of this study suggested that humans overestimate voluntary QF muscle torque when guided by perceptual sensations. It is also suggested that the produced EMG signals revealed a reliance on the VL muscle for knee extensor torque generation at sub-maximal levels. (C) 2003 Elsevier Science Ltd. All rights reserved.