Christensen Brooke A, Lin David C, Schwaner M Janneke, McGowan Craig P
Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA.
Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA.
J Exp Biol. 2022 Jan 15;225(2). doi: 10.1242/jeb.242954. Epub 2022 Jan 20.
Small bipedal hoppers, including kangaroo rats, are not thought to benefit from substantial elastic energy storage and return during hopping. However, recent species-specific material properties research suggests that, despite relative thickness, the ankle extensor tendons of these small hoppers are considerably more compliant than had been assumed. With faster locomotor speeds demanding higher forces, a lower tendon stiffness suggests greater tendon deformation and thus a greater potential for elastic energy storage and return with increasing speed. Using the elastic modulus values specific to kangaroo rat tendons, we sought to determine how much elastic energy is stored and returned during hopping across a range of speeds. In vivo techniques were used to record tendon force in the ankle extensors during steady-speed hopping. Our data support the hypothesis that the ankle extensor tendons of kangaroo rats store and return elastic energy in relation to hopping speed, storing more at faster speeds. Despite storing comparatively less elastic energy than larger hoppers, this relationship between speed and energy storage offers novel evidence of a functionally similar energy storage mechanism, operating irrespective of body size or tendon thickness, across the distal muscle-tendon units of both small and large bipedal hoppers.
小型双足跳跃动物，包括更格卢鼠，被认为在跳跃过程中无法从大量的弹性能量储存和回返中受益。然而，最近针对特定物种的材料特性研究表明，尽管相对较薄，但这些小型跳跃动物的踝伸肌腱比之前设想的更具柔韧性。随着更快的运动速度需要更高的力量，较低的肌腱刚度表明肌腱变形更大，因此随着速度增加，弹性能量储存和回返的潜力也更大。利用更格卢鼠肌腱特有的弹性模量值，我们试图确定在一系列速度的跳跃过程中储存和回返了多少弹性能量。采用体内技术记录稳定速度跳跃过程中踝伸肌的肌腱力。我们的数据支持这样的假设，即更格卢鼠的踝伸肌腱根据跳跃速度储存和回返弹性能量，速度越快储存越多。尽管与大型跳跃动物相比储存的弹性能量相对较少，但这种速度与能量储存之间的关系提供了新的证据，表明在大小型双足跳跃动物的远端肌肉 - 肌腱单元中，存在一种功能类似的能量储存机制，其运行与身体大小或肌腱厚度无关。
