Nordez Antoine, Cornu Christophe, McNair Peter
Laboratoire Motricité, Interactions, Performance, JE 2438, UFR STAPS, Université de Nantes, France.
Clin Biomech (Bristol). 2006 Aug;21(7):755-60. doi: 10.1016/j.clinbiomech.2006.03.005. Epub 2006 May 3.
The aim of this study was to assess the effects of static stretching on hamstring passive stiffness calculated using different data reduction methods.
Subjects performed a maximal range of motion test, five cyclic stretching repetitions and a static stretching intervention that involved five 30-s static stretches. A computerised dynamometer allowed the measurement of torque and range of motion during passive knee extension. Stiffness was then calculated as the slope of the torque-angle relationship fitted using a second-order polynomial, a fourth-order polynomial, and an exponential model. The second-order polynomial and exponential models allowed the calculation of stiffness indices normalized to knee angle and passive torque, respectively.
Prior to static stretching, stiffness levels were significantly different across the models. After stretching, while knee maximal joint range of motion increased, stiffness was shown to decrease. Stiffness decreased more at the extended knee joint angle, and the magnitude of change depended upon the model used. After stretching, the stiffness indices also varied according to the model used to fit data. Thus, the stiffness index normalized to knee angle was found to decrease whereas the stiffness index normalized to passive torque increased after static stretching.
Stretching has significant effects on stiffness, but the findings highlight the need to carefully assess the effect of different models when analyzing such data.
本研究旨在评估静态拉伸对使用不同数据简化方法计算出的腘绳肌被动僵硬度的影响。
受试者进行最大活动范围测试、五次循环拉伸重复以及一次包含五次30秒静态拉伸的静态拉伸干预。一台计算机化测力计可测量被动膝关节伸展过程中的扭矩和活动范围。然后使用二阶多项式、四阶多项式和指数模型拟合扭矩-角度关系曲线，将曲线斜率计算为僵硬度。二阶多项式模型和指数模型分别允许计算根据膝关节角度和被动扭矩归一化的僵硬度指数。
在静态拉伸之前，各模型的僵硬度水平存在显著差异。拉伸后，膝关节最大活动范围增加，僵硬度降低。在膝关节伸展角度处僵硬度下降更多，且变化幅度取决于所使用的模型。拉伸后，僵硬度指数也因用于拟合数据的模型而异。因此，发现静态拉伸后，根据膝关节角度归一化的僵硬度指数降低，而根据被动扭矩归一化的僵硬度指数增加。
拉伸对僵硬度有显著影响，但研究结果强调在分析此类数据时需要仔细评估不同模型的影响。
