Viscoelastic properties of striated muscle are often measured using length perturbation analysis and quantified as a complex modulus, whose elastic and viscous components reflect the energy-storage and energy-absorbing properties of the tissue, respectively. The energy stored as inertia is commonly ignored due to the small size of samples examined, typically <1 mm. Considering recent advances in tissue engineering to generate muscle tissues of larger sizes, we questioned whether ignoring the inertial artifact was still reasonable in these samples. To answer this question, we derived and solved the one-dimensional wave equation that describes the propagation of strain along the length of a sample. The inertial artifact was predicted to contaminate the elastic modulus with (2πf)²L₀²ρ/6, where f is perturbation frequency, L₀ is muscle length, and ρ is muscle density. We then measured viscoelastic properties up to 500 Hz in mouse skeletal muscle fibers at long (4.8 mm) and short (<1 mm) lengths and up to 100 Hz in rat cardiac slices at long (10–12 mm) and short (<2 mm) lengths. We found the elastic modulus of long preparations was elevated as frequency increased and was about half the magnitude of that predicted by the model. While the prediction tended to overestimate the measured inertial artifact, these results provided some validity to the model. We used the predicted artifact as an overly conservative estimate of error that might arise in a mechanics assay of mammalian striated muscle, whose nominal resting stiffness is on the order 100 kN m⁻². We found that muscle lengths of <1 mm resulted in negligible inertial artifact (<0.5% error) for perturbation frequencies under 250 Hz. Muscle samples longer than 5 mm, on the other hand, would result in >5% error at frequencies of 200 Hz and higher.

横纹肌的粘弹性特性通常使用长度扰动分析来测量，并量化为复数模量，其弹性和粘性分量分别反映了组织的能量存储和能量吸收特性。由于所检查的样品尺寸较小（通常为 <1 mm），以惯性形式存储的能量通常被忽略。考虑到组织工程在产生更大尺寸肌肉组织方面的最新进展，我们质疑在这些样本中忽略惯性伪影是否仍然合理。为了回答这个问题，我们推导并求解了描述应变沿样本长度传播的一维波动方程。惯性伪影预计会污染弹性模量 (2 πf ) ² L ₀ ² ρ /6，其中f是扰动频率， L ₀是肌肉长度， ρ是肌肉密度。然后，我们测量了长 (4.8 mm) 和短 (<1 mm) 长度的小鼠骨骼肌纤维的高达 500 Hz 的粘弹性特性，以及长 (10–12 mm) 和短 (<2 mm) 的大鼠心脏切片的高达 100 Hz 的粘弹性特性。毫米）长度。我们发现长制剂的弹性模量随着频率的增加而升高，大约是模型预测的一半。虽然预测往往高估了测量到的惯性伪影，但这些结果为模型提供了一定的有效性。我们使用预测的伪影作为对哺乳动物横纹肌力学分析中可能出现的误差的过于保守的估计，其标称静息刚度约为 100 kN m ^-2 。 我们发现，对于 250 Hz 以下的扰动频率，<1 mm 的肌肉长度导致的惯性伪影可以忽略不计（<0.5% 误差）。另一方面，长度超过 5 毫米的肌肉样本在 200 Hz 及更高的频率下会导致 >5% 的误差。