Hisey Brandon, Leonard Tim R, Herzog Walter
Human Performance Lab., Faculty of Kinesiology, University of Calgary, 2500 University Drive N.W. Calgary, Alberta, Canada T2N 1N4.
Human Performance Lab., Faculty of Kinesiology, University of Calgary, 2500 University Drive N.W. Calgary, Alberta, Canada T2N 1N4.
J Biomech. 2009 Jul 22;42(10):1488-1492. doi: 10.1016/j.jbiomech.2009.03.046. Epub 2009 May 13.
It is generally accepted that force enhancement in skeletal muscles increases with increasing stretch magnitudes. However, this property has not been tested across supra-physiological stretch magnitudes and different muscle lengths, thus it is not known whether this is a generic property of skeletal muscle, or merely a property that holds for small stretch magnitudes within the physiological range. Six cat soleus muscles were actively stretched with magnitudes varying from 3 to 24 mm at three different parts of the force-length relationship to test the hypothesis that force enhancement increases with increasing stretch magnitude, independent of muscle length. Residual force enhancement increased consistently with stretch amplitudes on the descending limb of the force-length relationship up to a threshold value, after which it reached a plateau. Force enhancement did not increase with stretch amplitude on the ascending limb of the force-length relationship. Passive force enhancement was observed for all test conditions, and paralleled the behavior of the residual force enhancement. Force enhancement increased with stretch magnitude when stretching occurred at lengths where there was natural passive force within the muscle. These results suggest that force enhancement does not increase unconditionally with increasing stretch magnitude, as is generally accepted, and that increasing force enhancement with stretch appears to be tightly linked to that part of the force-length relationship where there is naturally occurring passive force.
人们普遍认为，骨骼肌中的力量增强会随着拉伸幅度的增加而增加。然而，这一特性尚未在超生理拉伸幅度和不同肌肉长度的情况下进行测试，因此尚不清楚这是骨骼肌的普遍特性，还是仅仅是生理范围内小拉伸幅度所具有的特性。六只猫的比目鱼肌在力-长度关系的三个不同部分被主动拉伸，拉伸幅度从3毫米到24毫米不等，以检验力量增强随拉伸幅度增加而增加这一假设，且与肌肉长度无关。在力-长度关系的下降支上，残余力量增强随着拉伸幅度持续增加，直至达到阈值，之后达到平稳状态。在力-长度关系的上升支上，力量增强并未随拉伸幅度增加。在所有测试条件下均观察到被动力增强，且与残余力量增强的行为相似。当在肌肉内存在自然被动力的长度处进行拉伸时，力量增强随拉伸幅度增加。这些结果表明，力量增强并非如普遍所认为的那样随拉伸幅度增加而无条件增加，且力量增强随拉伸增加似乎与力-长度关系中存在自然被动力的部分紧密相关。
