Meeting Abstract
88.1 Sunday, Jan. 6 Comparison of walking mechanics in an arboreal and a terrestrial primate BISHOP, K.L.*; O’NEILL, M.; SCHMITT, D.; Florida International University; Stony Brook University; Duke University kristin.bishop@fiu.edu
Animals have several mechanisms available that may reduce their muscular effort while walking. One is to adopt an inverted pendulum movement of center of mass to exchange potential and kinetic energy needed to lift and accelerate the center of mass. Alternatively, animals can reduce the energy lost through redirecting the path of the center of mass, known as collisional energy loss. Previous work has shown that some animals use the inverted pendulum mechanism less effectively than others, but it is not known whether those animals accept a higher cost for locomotion or compensate by using other energy saving mechanisms such as reducing collisional energy loss. Arboreal animals may be unable to use the inverted pendulum mechanism, and if so, they may compensate by reducing collisional losses. In this study we compare the walking mechanics of two species of lemurs, Lemur catta, the most terrestrial of the lemurs, and Eulemur fulvus, an exclusively arboreal species. Individuals of both species were videorecorded while walking across a force plate that was either flat or had a pole attached, simulating arboreal locomotion, to record the kinematics and kinetics of their locomotion. We found that L. catta was capable of having very high energy recovery, with a maximum energy recovery of 71%, comparable to that found in dogs and humans. Recovery values were high in this species for both ground and pole. E. fulvus had lower energy recovery on both ground and pole, with a maximum recovery below 50%. Thus the use of an arboreal support does not drive mechanical patterns, but arboreal adaptations appear to have an import effect suggesting that effective arboreal movement may be inconsistent with energy recovery. Kinematic analysis and comparisons of collision fraction were used to explain the differences in energy recovery between the terrestrial and arboreal species.
