Meeting Abstract

14.3  Thursday, Jan. 3  Motions of the running horse and cheetah revisited: basic mechanics of the transverse and rotary gallop BERTRAM, JEA; Univ. of Calgary, Calgary, Canada jbertram@ucalgary.ca

Understanding the organization and meaning of mammalian gaits is important to interpreting the structural requirements and functional capabilities of their morphology. The galloping gaits, as both the fastest and most complex asymmetrical gaits have attracted much interest. Early studies identified two fundamental types of gallop variously called the diagonal or transverse gallop and the lateral or rotary gallop. These were fully described and classified in a classic paper by Hildebrand, �Motions of the running horse and cheetah� (1959) where the transverse gallop was epitomized by the horse and the rotary gallop by the cheetah. Yet in spite of a great deal of often highly technical investigation into the galloping gait over the intervening half century, very little is understood about the meaning of the particular footfall pattern displayed by galloping quadrupeds. Interpretation of the relatively subtle differences between these forms of the gallop requires an understanding of what is being accomplished by the body motions that constitute the gait. This presentation explains the basic mechanics that underlie these two forms of the terrestrial gallop and highlights the factors that distinguish the functional characteristics of each. The transverse gallop of the horse is defined as a �forelimb lead� gallop and the rotary gallop of the cheetah as a �hind limb lead� gallop. It is shown that the lead determines the mechanical differences between these two forms of gallop well beyond the lateral limb sequence usually used to characterize each.