Baudry Stéphane, Duchateau Jacques
Laboratory of Applied Biology, Université Libre de Bruxelles, Brussels, Belgium.
J Appl Physiol (1985). 2007 Apr;102(4):1394-401. doi: 10.1152/japplphysiol.01254.2006. Epub 2007 Jan 4.
Postactivation potentiation (PAP), a mechanism by which the torque of a muscle twitch is increased following a conditioning contraction, is well documented in muscular physiology, but little is known about its effect on the maximal rate of torque development and functional significance during voluntary movements. The objective of this study was to investigate the PAP effect on the rate of isometric torque development of electrically induced and voluntary contractions. To that purpose, the electromechanical responses of the thumb adductor muscles to a single electrical stimulus (twitch), a train of 15 pulses at 250 Hz (HFT(250)), and during ballistic (i.e., rapid torque development) voluntary contractions at torque levels ranging from 10 to 75% of maximal voluntary contraction (MVC) were recorded before and after a conditioning 6-s MVC. The results showed that the rate of torque development was significantly (P < 0.001) increased after the conditioning MVC, but the effect was greater for the twitch ( approximately 200%) compared with the HFT(250) ( approximately 17%) or ballistic contractions (range: 9-24%). Although twitch potentiation was maximal immediately after the conditioning MVC, maximal potentiation for HFT(250) and ballistic contractions was delayed to 1 min after the 6-s MVC. Furthermore, the similar degree of potentiation for the rate of isometric torque development between tetanic and voluntary ballistic contractions indicates that PAP is not related to the modality of muscle activation. These observations suggest that PAP may be considered as a mechanism that can influence our contractions during daily tasks and can be utilized to improve muscle performance in explosive sports.
激活后增强效应（PAP）是一种在条件性收缩后肌肉抽搐扭矩增加的机制，在肌肉生理学中已有充分记载，但对于其在自主运动过程中对最大扭矩发展速率和功能意义的影响却知之甚少。本研究的目的是探讨PAP对电诱发收缩和自主收缩的等长扭矩发展速率的影响。为此，在进行6秒的最大自主收缩（MVC）条件性收缩前后，记录了拇指内收肌对单个电刺激（抽搐）、250赫兹的15个脉冲序列（HFT(250)）以及在扭矩水平为最大自主收缩（MVC）的10%至75%的弹道式（即快速扭矩发展）自主收缩过程中的机电反应。结果表明，在条件性MVC后，扭矩发展速率显著增加（P < 0.001），但与HFT(250)（约17%）或弹道式收缩（范围：9% - 24%）相比，抽搐的效应更大（约200%）。虽然抽搐增强在条件性MVC后立即达到最大值，但HFT(250)和弹道式收缩的最大增强延迟到6秒MVC后的1分钟。此外，强直收缩和自主弹道式收缩在等长扭矩发展速率上的增强程度相似，这表明PAP与肌肉激活方式无关。这些观察结果表明，PAP可被视为一种能够影响我们日常任务中收缩的机制，并且可用于提高爆发性运动中的肌肉表现。
