Meeting Abstract

14.4  Thursday, Jan. 3  Do Walking Mechanics in Cats Favor Stealth Over Economy? BISHOP, K.L.*; PAI, A.K.; SCHMITT, D.; University of California, Davis; Duke University; Duke University kvwbishop@ucdavis.edu

Many quadrupedal animals use pendulum-like mechanics to exchange kinetic energy (KE) and potential energy (PE), thereby reducing muscular work required for walking. Pendular mechanics are well characterized for cursorial specialists, but are poorly understood for less cursorial animals. The stealthy walking style of cats provides a good contrast to cursorial specialists, yet their gait mechanics have not been documented in detail. We tested the hypotheses that cats use a more crouched posture while walking and have lower mechanical energy recovery compared to cursors. We collected kinematic and force plate data for six adult cats. Using these data, we computed the PE and KE fluctuations throughout individual strides and calculated the percent recovery of mechanical energy and percent congruity of changes in PE and KE. Percent recovery was much lower in cats compared to more cursorial species at all walking speeds. Unlike previously studied mammals, percent recovery in cats did not vary as a function of forward velocity. Percent recovery had a strong relationship with footfall pattern, such that as the gait approached a walking trot, recovery was reduced. There was also an unexpectedly large amount of variation in diagonality in the walking gaits of cats compared to other mammals. Diagonality had a strong negative correlation with limb compression such that the cats used a more crouched posture as the gait approached a trot. The association between low energy recovery, the use of a more diagonal gait and having a more crouched posture suggests a tradeoff between stealthy walking and economy of locomotion.