Biophysics Laboratory, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA.
Eur J Appl Physiol. 2010 Jan;108(2):301-10. doi: 10.1007/s00421-009-1214-3. Epub 2009 Sep 26.
The purpose of this study was to investigate the acute effects of passive stretching on the electromechanical delay (EMD), peak twitch force (PTF), rate of force development (RFD), and compound muscle action potential (M-wave) amplitude during evoked twitches of the plantar flexor muscles. 16 men (mean age +/- SD = 21.1 +/- 1.7 years; body mass = 75.9 +/- 11.4 kg; height = 176.5 +/- 8.6 cm) participated in this study. A single, square-wave, supramaximal transcutaneous electrical stimulus was delivered to the tibial nerve before and after passive stretching. The stretching protocol consisted of nine repetitions of passive assisted stretching designed to stretch the calf muscles. Each repetition was held for 135 s separated by 5-10 s of rest. Dependent-samples t tests (pre- vs. post-stretching) were used to analyze the EMD, PTF, RFD, and M-wave amplitude data. There were significant changes (P < or = 0.05) from pre- to post-stretching for EMD (mean +/- SE = 4.84 +/- 0.31 and 6.22 +/- 0.34 ms), PTF (17.2 +/- 1.3 and 15.6 +/- 1.5), and RFD (320.5 +/- 24.5 and 279.8 +/- 28.2), however, the M-wave amplitude did not change (P > 0.05). These findings suggested that passively stretching the calf muscles affected the mechanical aspects of force production from the onset of the electrically evoked twitch to the peak twitch force. These results may help to explain the mechanisms underlying the stretching-induced force deficit that have been reported as either "mechanical" or "electrical" in origin.
本研究旨在探讨被动伸展对足底屈肌诱发 twitch 时的机电延迟（EMD）、峰值 twitch 力（PTF）、力发展速率（RFD）和复合肌肉动作电位（M 波）幅度的急性影响。16 名男性（平均年龄 +/- 标准差=21.1 +/- 1.7 岁；体重=75.9 +/- 11.4 千克；身高=176.5 +/- 8.6 厘米）参与了这项研究。在被动伸展前后，通过单次、方波、超强经皮电刺激传递至胫神经。伸展方案由 9 个被动辅助伸展重复组成，旨在伸展小腿肌肉。每个重复保持 135 秒，间隔 5-10 秒休息。采用独立样本 t 检验（伸展前与伸展后）分析 EMD、PTF、RFD 和 M 波幅度数据。EMD（均值 +/- SE=4.84 +/- 0.31 和 6.22 +/- 0.34 毫秒）、PTF（17.2 +/- 1.3 和 15.6 +/- 1.5）和 RFD（320.5 +/- 24.5 和 279.8 +/- 28.2）在伸展前与伸展后均有显著变化（P<或=0.05），而 M 波幅度无变化（P>0.05）。这些发现表明，被动伸展小腿肌肉会影响从电诱发 twitch 开始到峰值 twitch 力的机械力产生方面。这些结果可能有助于解释已报道的拉伸诱导力缺陷的机制，这些机制源自“机械”或“电”。
