102.1  Thursday, Jan. 7  Galloping at high speed: insights from cheetahs and racing greyhounds HUDSON, P.E.*; CORR, S.A.; WILSON, A.M.; Royal Veterinary College; Royal Veterinary College; Royal Veterinary College phudson@rvc.ac.uk

High speed locomotion is essential for the survival and success of many species. The cheetah is the fastest living land mammal with a reported maximum speed of to 28.6 ms^-1. Here we compare cheetahs to racing greyhounds which are similar in size and have been selectively bred for high speed sprints. Greyhounds, however, have a maximum speed of around 19 ms^-1 during a race. The reason for this difference is unclear and we attempt to shed light on this by comparing the kinematics and kinetics of galloping in cheetahs and greyhounds.

We have collected data from three cheetahs and six greyhounds to date. All animals chased a mechanical lure along a 90 m runway with an array of six to eight Kistler force plates embedded in it. Subjects were videoed from both sides using four AOS high speed cameras (1280 x 600, 1000fps).

Our data to date were recorded at disappointingly submaximal speeds (cheetah 15 ms^-1, greyhound 13ms^-1). At these speeds the cheetahs utilised longer stride lengths than greyhounds at a maximum of 5.3m for the cheetah and just 3.5m for the greyhound. In the forelimb, cheetahs had higher stance and swing times than greyhounds however duty factor was similar in the two species. In the hindlimbs, swing time was higher in the cheetahs than the greyhounds and stance times were similar in the two species so cheetahs had a slightly lower duty factor than greyhounds.

It would be interesting to have data for cheetahs at maximum speed. Analysis of wildlife documentary footage is difficult, however, such footage does demonstrate that wild cheetahs use higher stride frequencies than published values for greyhounds which may account for some of the “speed reserve”. In addition the greater range of spinal movement in cheetahs at full speed may enable cheetahs to extend their contact lengths more than greyhounds maintaining a constant duty factor.