Department of Kinesiology, University of New Hampshire, Durham 03824, USA.
Percept Mot Skills. 2012 Jun;114(3):847-56. doi: 10.2466/25.26.27.PMS.114.3.847-856.
Effect of contraction intensity [100%, 75%, 50%, and 25% maximum voluntary contraction (MVC)] and movement velocity [0 degrees (isometric)], 50 degrees, 100 degrees, 200 degrees, and 400 degrees/sec. [isovelocities]) on root mean square amplitude (SEMG-RMS) and median frequency power spectrum (SEMG-MNF) of vastus lateralis (VL) surface electromyography was investigated with ten healthy female university students. Peak torque (PT), mean torque (MT), SEMG-MNF, and SEMG-RMS, analyzed using separate repeated-measures analyses of variance (p < or = .05), indicated: (1) an inverse relation between PT and MT and movement velocity, (2) greater SEMG-MNF values during all isovelocity conditions compared with isometric conditions, with highest values occurring at 50 degrees /sec. and at 100% and 75% MVC, and (3) at all contraction intensities SEMG-RMS values were higher during dynamic movements than isometric movements and highest at 200 degrees /sec. Isovelocity contractions were inferred to facilitate a greater recruitment of fast-twitch fibers (via increased SEMG-MNF), which was intensified at 50 degrees /sec., whereas greater overall muscle activation was found at 200 degrees /sec.
研究了 10 名健康女性大学生在收缩强度[100%、75%、50%和 25%最大自主收缩（MVC）]和运动速度[0 度（等长）、50 度、100 度、200 度和 400 度/秒[等速]）对股外侧肌（VL）表面肌电图的均方根振幅（SEMG-RMS）和中值频率功率谱（SEMG-MNF）的影响。使用单独的重复测量方差分析（p < 或 =.05）分析了峰值扭矩（PT）、平均扭矩（MT）、SEMG-MNF 和 SEMG-RMS，结果表明：（1）PT 和 MT 与运动速度呈反比关系；（2）在所有等速条件下，SEMG-MNF 值均大于等长条件，在 50 度/秒和 100%和 75%MVC 时达到最高值；（3）在所有收缩强度下，动态运动时 SEMG-RMS 值高于等长运动，在 200 度/秒时达到最高值。等速收缩被推断为促进快肌纤维的更大募集（通过增加 SEMG-MNF），在 50 度/秒时加剧，而在 200 度/秒时发现总体肌肉激活更大。
