Corr David T, Leverson Glen E, Vanderby Ray, Best Thomas M
Human Performance Laboratory, University of Calgary, Calgary, Canada.
Med Sci Sports Exerc. 2003 Sep;35(9):1581-8. doi: 10.1249/01.MSS.0000084423.39529.C5.
To better understand the mechanical behavior of healing skeletal muscle; specifically the tissue's response after acute eccentric stretch injury.
Rabbit tibialis anterior (TA) muscle tendon units were subjected to an in vivo single stretch (eccentric) injury and mechanically evaluated (constant rate elongation to failure) at 1, 3, and 7 d postinjury. In addition to a traditional linear analysis (linear stiffness and failure load), an existing nonlinear rheological model was modified to interpret the experimental load-to-failure data. The models' performance were evaluated and discussed.
No significant injury effect was observed, either within or between groups, across the 7-d healing interval, using the linear analysis. However, interpretation of the data using our nonlinear phenomenological model identified significant changes in mechanical behavior that went undetected by linear analyses. Percent differences, between injured and contralateral control limbs, of model parameter estimates were analyzed. Nonparametric statistical analysis illustrated significant changes in the first-order stiffness (k1) throughout the 7-d healing interval. Model simulations using mean values of each parameter revealed increased low-load tissue compliance after injury, with a decrease in linear slope that recovered steadily toward control values by day 7. At 7 d postinjury, virtually no differences were observed between injured and sham control tissues.
Our findings suggest that acute eccentric injury increases the muscle's compliance 24 h after injury, with a steady recovery to uninjured values by the 7th day, yet these changes went undetected by linear analysis. Therefore, nonlinear analysis is necessary to recognize valuable information contained in the low-load region and to quantify important biomechanical phenomena of stretch-injured healing skeletal muscle.
更好地理解愈合过程中骨骼肌的力学行为；特别是急性离心拉伸损伤后组织的反应。
对兔胫前肌（TA）肌腱单元进行体内单次拉伸（离心）损伤，并在损伤后1、3和7天进行力学评估（恒定速率伸长至破坏）。除了传统的线性分析（线性刚度和破坏载荷）外，对现有的非线性流变模型进行修改，以解释实验中的破坏载荷数据。对模型的性能进行了评估和讨论。
使用线性分析，在7天的愈合期内，组内和组间均未观察到显著的损伤效应。然而，使用我们的非线性唯象模型对数据进行解释时，发现了线性分析未检测到的力学行为的显著变化。分析了损伤肢体与对侧对照肢体模型参数估计值的百分比差异。非参数统计分析表明，在整个7天的愈合期内，一阶刚度（k1）有显著变化。使用每个参数的平均值进行的模型模拟显示，损伤后低负荷组织顺应性增加，线性斜率降低，到第7天逐渐恢复到对照值。损伤后7天，损伤组织与假手术对照组织之间几乎没有差异。
我们的研究结果表明，急性离心损伤后24小时肌肉顺应性增加，到第7天稳定恢复到未损伤值，但这些变化通过线性分析未被检测到。因此，非线性分析对于识别低负荷区域中包含的有价值信息以及量化拉伸损伤愈合骨骼肌的重要生物力学现象是必要的。
