Centre for Sports Medicine and Human Performance, Brunel University, London, UK.
J Electromyogr Kinesiol. 2012 Dec;22(6):947-53. doi: 10.1016/j.jelekin.2012.06.004. Epub 2012 Jul 24.
Tendon stiffness is calculated by dividing changes in tendon force by tendon elongation. For this purpose, participants are commonly asked to perform a maximal muscle contraction ("active" method). Alternatively tendon elongation can be achieved by means of a passive joint rotation ("passive" method). The purpose of this study was to compare Achilles tendon stiffness obtained from both methods across different tendon strain rates. Twenty adults performed a series of ramped maximum isometric plantarflexions of different durations. Passive ankle rotations of different angular velocities were also performed. Achilles tendon stiffness was obtained from a combination of motion analysis, isokinetic dynamometry and ultrasonography and compared across methods at three strain rates. At all strain rates, tendon stiffness obtained from the active method was 6% greater compared to the passive method. In spite of this systematic bias, there was good agreement between the methods. Intraclass correlation coefficients were greater than 0.98, and more than 95% of data points fell into the 95% confidence intervals. This agreement will be acceptable in many research contexts. We also found a linear increase in tendon stiffness with increasing strain rate, which must be taken into consideration when interpreting or reporting tendon stiffness.
肌腱刚度是通过将肌腱力的变化除以肌腱伸长来计算的。为此，通常要求参与者进行最大肌肉收缩（“主动”方法）。或者，可以通过被动关节旋转（“被动”方法）来实现肌腱伸长。本研究的目的是比较两种方法在不同肌腱应变速率下获得的跟腱刚度。二十名成年人进行了一系列不同持续时间的斜坡式最大等长跖屈。还进行了不同角速度的被动踝关节旋转。通过运动分析、等速测力和超声检查相结合的方法获得跟腱刚度，并在三种应变速率下比较两种方法。在所有应变速率下，主动方法获得的肌腱刚度比被动方法高 6%。尽管存在这种系统偏差，但两种方法之间具有良好的一致性。组内相关系数大于 0.98，超过 95%的数据点落入 95%置信区间内。在许多研究背景下，这种一致性是可以接受的。我们还发现肌腱刚度随应变速率的线性增加，在解释或报告肌腱刚度时必须考虑到这一点。
