Jumping mechanics of desert kangaroo rats

M. Janneke Schwaner, David C. Lin, Craig P. McGowan

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Kangaroo rats are small bipedal desert rodents that use erratic vertical jumps to escape predator strikes. In this study we examined how individual hind limb joints of desert kangaroo rats (Dipodomys deserti) power vertical jumps across a range of heights. We hypothesized that increases in net work would be equally divided across hind limb joints with increases in jump height. To test this hypothesis, we used an inverse dynamics analysis to quantify the mechanical output from the hind limb joints of kangaroo rats jumping vertically over a wide range of heights. The kangaroo rats in this study reached maximal jump heights up to ∼9-times hip height. Net joint work increased significantly with jump height at the hip, knee and ankle, and decreased significantly at the metatarsal-phalangeal joint. The increase in net work generated by each joint was not proportional across joints but was dominated by the ankle, which ranged from contributing 56% of the work done on the center of mass at low jumps to 70% during the highest jumps. Therefore, the results of this study did not support our hypothesis. However, using an anatomical model, we estimated that a substantial proportion of the work delivered at the ankle (48%) was transferred from proximal muscles via the biarticular ankle extensors.
Original languageEnglish
JournalJournal of Experimental Biology
Volume221
Issue number22
DOIs
Publication statusPublished - 1 Nov 2018
Externally publishedYes

Funding

This work was supported by National Science Foundation (NSF 1553550 to C.P.M.) and Army Research Office (ARO 66554-EG to D.C.L. and C.P.M.).

FundersFunder number
National Science FoundationNSF 1553550
Army Research OfficeARO 66554-EG
National Science Foundation1553550

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