School of Kinesiology, Arthur and Sonia Labatt Health Sciences Building, University of Western Ontario, London, Ontario N6A 5B9, Canada.
Muscle Nerve. 2011 Jun;43(6):859-65. doi: 10.1002/mus.21993. Epub 2011 Apr 1.
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.
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.
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%).
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.
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。
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。
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。
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。
