ABSTRACT
The metabolic cost associated with locomotion represents a significant part of an animal’s metabolic energy budget. Therefore, understanding the ways in which animals manage the energy required for locomotion by controlling muscular effort is critical to understanding limb design and the evolution of locomotor behavior. Many quadrupedal animals, particularly those that specialize in long distance steady locomotion, do, in fact, reduce the muscular contribution required for walking by adopting pendulumlike center of mass movements that facilitate exchange between kinetic energy (KE) and potential energy (PE) [1-4]. However, animals that are not specialized for long distance steady locomotion may face a more complex set of requirements, some of which may conflict with the efficient exchange of mechanical energy. For example, the “stealthy” walking style of cats may demand slow movements performed with the center of mass close to the ground. Force plate and video data show that domestic cats (Felis catus, Linnaeus, 1758) have lower mechanical energy recovery than mammals specialized for distance. A strong negative correlation was found between mechanical energy recovery and diagonality in the footfalls and there was also a negative correlation between limb compression and diagonality of footfalls, so that more crouched postures tended to have greater diagonality. These data show a previously unrecognized mechanical relationship in which crouched postures are associated with changes in the footfall pattern which is in turn related to reduced mechanical energy recovery.
