Davis Daniel J, Ray Samuel F, Franz Jason R, Takahashi Kota Z
Department of Health and Kinesiology, University of Utah, Salt Lake City, Utah, United States.
Department of Physical Medicine & Rehabilitation, Northwestern University Prosthetics-Orthotics Center, Northwestern University, Evanston, Illinois, United States.
J Appl Physiol (1985). 2025 Aug 1;139(2):509-516. doi: 10.1152/japplphysiol.00045.2025. Epub 2025 Jul 18.
Numerous assistive devices have been designed to improve mobility by improving propulsion and reducing the metabolic cost of walking. Stiff carbon fiber insoles integrated into footwear have emerged as a potentially viable option by increasing longitudinal bending stiffness, providing additional leverage for the ankle joint musculature, and increasing soleus force output. However, it remains unknown whether this increased leverage comes with a metabolic penalty at the individual muscle level, which would create a translational barrier for prescribing carbon fiber insoles as targeted interventions. We incorporated motion capture, cine B-mode ultrasound, and electromyography data ( = 14) into a bioenergetic model to estimate soleus metabolic cost. Participants walked on an instrumented treadmill at 1.25, 1.75, and 2.0 m/s wearing standardized shoes containing either no carbon fiber insole (low stiffness), a 1.6-mm-thick insole (medium stiffness), or a 3.2-mm-thick insole (high stiffness). We found a significant main effect ( < 0.001) of walking speed, but not stiffness, for estimated soleus average metabolic power. These results indicate that increases in soleus force output while walking due to increased footwear bending stiffness do not statistically significantly alter muscle-specific metabolic cost, likely due to concomitant reductions in fascicle shortening velocity. As such, carbon fiber insoles may be a particularly useful assistive device for walking in those with ankle plantarflexion deficits. Increasing footwear bending stiffness via carbon fiber insoles has been shown to reduce soleus fascicle shortening velocity and increase force output. Here, we used a bioenergetic model to estimate the metabolic energy consumed by the soleus muscle with increasing footwear stiffness across walking speeds. Footwear stiffness did not statistically significantly alter estimated soleus muscle energy consumption at any speed, highlighting carbon fiber insoles' capacity to increase muscle force without a clear metabolic penalty.
人们设计了许多辅助装置，旨在通过改善推进力和降低行走的代谢成本来提高行动能力。集成在鞋类中的硬质碳纤维鞋垫已成为一种潜在可行的选择，它可以增加纵向弯曲刚度，为踝关节肌肉组织提供额外的杠杆作用，并增加比目鱼肌的力量输出。然而，在个体肌肉水平上，这种增加的杠杆作用是否会带来代谢代价仍不清楚，这将为将碳纤维鞋垫作为针对性干预措施的处方设置一个转化障碍。我们将运动捕捉、动态B型超声和肌电图数据（n = 14）纳入生物能量模型，以估计比目鱼肌的代谢成本。参与者穿着标准化鞋子在仪器化跑步机上以1.25、1.75和2.0米/秒的速度行走，这些鞋子分别不含碳纤维鞋垫（低刚度）、1.6毫米厚的鞋垫（中等刚度）或3.2毫米厚的鞋垫（高刚度）。我们发现，对于估计的比目鱼肌平均代谢功率，行走速度有显著的主效应（p < 0.001），而刚度没有。这些结果表明，由于鞋类弯曲刚度增加，行走时比目鱼肌力量输出的增加在统计学上并没有显著改变肌肉特异性代谢成本，这可能是由于肌束缩短速度同时降低所致。因此，碳纤维鞋垫对于踝关节跖屈功能不全的人行走可能是一种特别有用的辅助装置。通过碳纤维鞋垫增加鞋类弯曲刚度已被证明可以降低比目鱼肌肌束缩短速度并增加力量输出。在这里，我们使用生物能量模型来估计随着鞋类刚度增加，比目鱼肌在不同行走速度下消耗的代谢能量。在任何速度下，鞋类刚度在统计学上都没有显著改变估计的比目鱼肌能量消耗，这突出了碳纤维鞋垫在增加肌肉力量而无明显代谢代价方面的能力。
