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首页> 外文期刊>Journal of Biomechanics >Quadriceps femoris electromyogram during concentric, isometric and eccentric phases of fatiguing dynamic knee extensions
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Quadriceps femoris electromyogram during concentric, isometric and eccentric phases of fatiguing dynamic knee extensions

机译：股四头肌肌电图在疲劳的动态膝关节伸展疲劳的同心，等距和偏心阶段

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摘要

The objective of this study was to examine the superficial quadriceps femoris (QF) muscle electromyogram (EMG) during fatiguing knee extensions. Thirty young adults were evaluated for their one-repetition maximum (IRM) during a seated, right-leg, inertial knee extension. All subjects then completed a single set of repeated knee extensions at 50% IRM, to failure. Subjects performed a knee extension (concentric phase), held the weight with the knee extended for 2s (isometric phase), and lowered the weight in a controlled manner (eccentric phase). Raw EMG of the vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF) muscles were full-wave rectified, integrated and normalized to the IRM EMG, for each respective phase and repetition. The EMG median frequency (f(med)) was computed during the isometric phase. An increase in QF muscle EMG was observed during the concentric phase across the exercise duration. VL EMG was greater than the VM and RF muscles during the isometric phase, in which no significant changes occurred in any of the muscles across the exercise duration. A significant decrease in EMG across the exercise duration was observed during the eccentric phase, with the VL EMG greater than the VM and RF muscles. A greater decrease in VL and RF muscle f(med) during the isometric phase, than the VM muscle, was observed with no gender differences. The findings demonstrated differential recruitment of the superficial QF muscle, depending on the contraction mode during dynamic knee extension exercise, where VL muscle dominance appears to manifest across the concentric-isometric-eccentric transition. (C) 2004 Elsevier Ltd. All rights reserved.
机译：这项研究的目的是检查疲劳的膝盖伸展过程中股浅四头肌（QF）肌肉肌电图（EMG）。在坐着的右腿惯性膝盖伸展过程中，对30名年轻成年人的单次重复最大值（IRM）进行了评估。然后，所有受试者以50％IRM完成单组重复的膝盖伸展，直至失败。受试者进行膝盖伸展（同心阶段），膝盖伸直2秒钟保持体重（等距阶段），并以受控方式降低体重（偏心阶段）。分别对每个阶段和重复进行全波整流，整合和归一化IRM EMG的股内侧肌（VM），股外侧肌（VL）和股直肌（RF）的原始EMG。在等轴测阶段计算EMG中值频率（f（med））。在整个运动过程中的同心阶段，观察到QF肌肉的肌电图增加。在等轴测阶段，VL EMG大于VM和RF肌肉，其中在整个运动过程中，任何肌肉均未发生明显变化。在离心运动期间，观察到整个运动过程中EMG的显着下降，其中VL EMG大于VM和RF肌肉。在等轴测阶段，VL和RF肌肉f（med）的下降比VM肌肉更大，并且没有性别差异。研究结果表明，根据动态膝关节伸展运动期间的收缩模式，浅层QF肌肉的募集有所不同，其中VL肌肉的支配力似乎在同心-等距-偏心过渡中表现出来。 （C）2004 Elsevier Ltd.保留所有权利。

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