肱三头肌在自愿次最大收缩时的增效作用。
Potentiation of the triceps brachii during voluntary submaximal contractions.
机构信息
School of Kinesiology, Arthur and Sonia Labatt Health Sciences Building, University of Western Ontario, London, Ontario N6A 5B9, Canada.
出版信息
Muscle Nerve. 2011 Jun;43(6):859-65. doi: 10.1002/mus.21993. Epub 2011 Apr 1.
INTRODUCTION
The effects of postactivation potentiation (PAP) on evoked contractions are well understood, but less is known about the effect of PAP on voluntary submaximal contractions. Using a measure of neuromuscular efficiency (NME) [NME = (mV EMG / Nm torque)] we explored the effects of PAP in the triceps brachii at two muscle lengths.
METHODS
Evoked twitch and NME were compared at short (40° elbow flexion) and long (120°) muscle lengths. At each length, 12 subjects performed a contraction of 25% maximum voluntary contraction (MVC) torque before and after a potentiating MVC.
RESULTS
Twitch torque potentiated more at short length (216.9 ± 169.3%) than at long length (77.3 ± 32.6%), but PAP moderately improved NME only at short length (12.2 ± 8.7%).
CONCLUSIONS
The greater capacity for PAP at the short length is reflected by greater NME. Compared with evoked responses, the relatively small change in NME suggests a different and more modest role of PAP during voluntary submaximal contractions.
简介
人们对动作激活后增强（PAP）对诱发收缩的影响已有深入了解，但对 PAP 对自愿性次最大收缩的影响知之甚少。本研究使用神经肌肉效率（NME）的一种度量[NME =（mV EMG / Nm 扭矩）]，探索了肱三头肌在两种肌肉长度下的 PAP 效应。
方法
在短（40°肘弯曲）和长（120°）肌肉长度下比较诱发的 twitch 和 NME。在每个长度下，12 名受试者在增强的 MVC 之前和之后进行 25%最大自愿收缩（MVC）扭矩的收缩。
结果
twitch 扭矩在短长度（216.9 ± 169.3%）上的增强幅度大于长长度（77.3 ± 32.6%），但 PAP 仅在短长度（12.2 ± 8.7%）上适度提高了 NME。
结论
短长度上更大的 PAP 能力反映了更大的 NME。与诱发反应相比，NME 的相对较小变化表明 PAP 在自愿性次最大收缩期间具有不同且更为适度的作用。
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