MCGOWAN, C.P.*; BAUDINETTE, R.V.; BIEWENER, A.A.; Harvard University, Concord Field Station; University of Adelaide, Australia; Harvard University, Concord Field Station: Leaping and Landing; Mechanical Power in Yellow-foot Rock Wallabies.

Much of what we know about animal locomotion has come from studies of animals moving at steady speeds over level surfaces. Yet in the wild animals are faced with much more variable environments in which they must maneuver. It is likely these non-steady actives that place the greatest demands on the musculoskeletal system of animals. The goal of this study was to examine how yellow-foot rock wallabies (Petrogale xanthopus), a species that inhabits steep rocky cliffs, produce and modulate mechanical power in steep leaping and landing maneuvers. In the wild, these animals have been seen to make leaps to well over five times their hip height and land from drops twice that high. In this experiment, five adult animals were hopped on an outdoor runway containing a stepped ledge 110 cm high (over three times hip height). High-speed video (250Hz, Photron Fastcam) was recorded from the lateral aspect and synchronized with the ground reaction forces measured via a forceplate (Kistler/Bioware) mounted in the runway. Points along the leg, body and tail were marked with white paint for kinematic analysis. The wallabies were hopped in both directions such that take off and landing occurred on the forceplate. Analysis of these data will focus on the changes in mechanical energy as the animals accelerate in leaping and decelerate in landing. An inverse dynamics analysis will combine kinematics and ground reaction forces to calculate joint power and determine which muscle groups in the leg are most active in modulating power in these two activities. Preliminary results suggest that the peak power produced in leaping by these animals is very high and the underlaying mechanics should prove very exciting.