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Christensen BA, Lin DC, Schwaner MJ, McGowan CP. Elastic energy storage across speeds during steady-state hopping of desert kangaroo rats (Dipodomys deserti). J Exp Biol 2022; 225:273978. [PMID: 35019972 DOI: 10.1242/jeb.242954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 12/30/2021] [Indexed: 11/20/2022]
Abstract
Small bipedal hoppers, including kangaroo rats, are thought to not 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 offer 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.
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Affiliation(s)
- Brooke A Christensen
- Department of Biological Sciences, University of Idaho, Moscow ID, USA.,Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine CA, USA
| | - David C Lin
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman WA, USA.,Department of Integrative Physiology and Neuroscience, Washington State University, Pullman WA, USA.,Washington Center for Muscle Biology, Washington State University, Pullman WA, USA
| | - M Janneke Schwaner
- Department of Biological Sciences, University of Idaho, Moscow ID, USA.,Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine CA, USA
| | - Craig P McGowan
- Department of Biological Sciences, University of Idaho, Moscow ID, USA.,Washington Center for Muscle Biology, Washington State University, Pullman WA, USA.,Keck School of Medicine of the University of Southern California, Los Angeles CA, USA
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