Lee Hae-Dong, Herzog Walter
Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4.
J Physiol. 2002 Nov 15;545(1):321-30. doi: 10.1113/jphysiol.2002.018010.
For electrically stimulated muscles, it has been observed that maximal muscle force during and after stretch is substantially greater than the corresponding isometric force. However, this observation has not been made for human voluntary contractions. We investigated the effects of active muscle stretch on muscle force production for in vivo human adductor pollicis (n = 12) during maximal voluntary contractions and electrically induced contractions. Peak forces during stretch, steady-state isometric forces following stretch, and passive forces following muscle deactivation were compared to the corresponding isometric forces obtained at optimal muscle length. Contractions with different stretch magnitudes (10, 20, and 30 deg at a constant speed of 10 deg s(-1)) and different speeds (10, 20, and 60 deg s(-1) over a range of 30 deg) were performed in triplicate in a random order, balanced design. We found three novel results: (i) there was steady-state force enhancement following stretch in voluntarily contracted muscles; (ii) some force enhancement persisted following relaxation of the muscle and (iii) force enhancement, for some stretch conditions, exceeded the maximum isometric force at optimal muscle length. We conclude from these results that voluntary muscle contraction produces similar force enhancement to that observed in the past with electrically stimulated preparations. Therefore, steady-state force enhancement may play a role in everyday movements. Furthermore, these results suggest that non-uniformities in sarcomere length do not, at least not exclusively, account for the force enhancement following active muscle stretch, and that the stretch magnitude-dependent passive force enhancement observed here may be responsible for the enhancement of force above the isometric reference force at optimal muscle length.
对于电刺激肌肉，已经观察到在拉伸过程中和拉伸后最大肌肉力量显著大于相应的等长力量。然而，对于人体自主收缩尚未有此观察结果。我们研究了在最大自主收缩和电诱发收缩期间，主动肌肉拉伸对体内人拇内收肌（n = 12）力量产生的影响。将拉伸过程中的峰值力量、拉伸后的稳态等长力量以及肌肉失活后的被动力与在最佳肌肉长度下获得的相应等长力量进行比较。以10° s(-1)的恒定速度进行不同拉伸幅度（10°、20°和30°）以及在30°范围内不同速度（10° s(-1)、20° s(-1)和60° s(-1)）的收缩，每组重复三次，采用随机顺序、平衡设计。我们发现了三个新结果：（i）在自主收缩的肌肉中，拉伸后存在稳态力量增强；（ii）肌肉放松后仍有一些力量增强持续存在；（iii）在某些拉伸条件下，力量增强超过了最佳肌肉长度下的最大等长力量。从这些结果我们得出结论，自主肌肉收缩产生的力量增强与过去在电刺激制剂中观察到的相似。因此，稳态力量增强可能在日常运动中起作用。此外，这些结果表明，肌节长度的不均匀性至少不是唯一导致主动肌肉拉伸后力量增强的原因，并且这里观察到的与拉伸幅度相关的被动力增强可能是导致在最佳肌肉长度下力量超过等长参考力量增强的原因。
