Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada V5A 1S6.
J R Soc Interface. 2021 Sep;18(182):20210484. doi: 10.1098/rsif.2021.0484. Epub 2021 Sep 29.
While skeletal muscle mass has been shown to decrease mass-specific mechanical work per cycle, it is not yet known how muscle mass alters contraction efficiency. In this study, we examined the effect of muscle mass on mass-specific metabolic cost and efficiency during cyclic contractions in simulated muscles of different sizes. We additionally explored how tendon and its stiffness alters the effects of muscle mass on mass-specific work, mass-specific metabolic cost and efficiency across different muscle sizes. To examine contraction efficiency, we estimated the metabolic cost of the cycles using established cost models. We found that for motor contractions in which the muscle was primarily active during shortening, greater muscle mass resulted in lower contraction efficiency, primarily due to lower mass-specific mechanical work per cycle. The addition of a tendon in series with the mass-enhanced muscle model improved the mass-specific work and efficiency per cycle with greater mass for motor contractions, particularly with a shorter excitation duty cycle, despite higher predicted metabolic cost. The results of this study indicate that muscle mass is an important determinant of whole muscle contraction efficiency.
虽然已经证明骨骼肌质量会降低每周期的比机械功，但目前尚不清楚肌肉质量如何改变收缩效率。在这项研究中，我们研究了肌肉质量对不同大小模拟肌肉中周期性收缩时比代谢成本和效率的影响。我们还探讨了肌腱及其刚度如何改变肌肉质量对不同肌肉大小下比功、比代谢成本和效率的影响。为了研究收缩效率，我们使用已建立的成本模型估计了周期的代谢成本。我们发现，对于主要在缩短过程中活跃的运动收缩，较大的肌肉质量会导致收缩效率降低，这主要是由于每周期的比机械功降低。在质量增强的肌肉模型中串联添加肌腱可以提高周期性运动的比功和效率，尤其是在较短的激励占空比下，尽管预测代谢成本更高。这项研究的结果表明，肌肉质量是整个肌肉收缩效率的重要决定因素。
