JOURNAL MAMMALOGY : MOTIONS OF THE RUNNING CHEETAH AND HORSE

Abstract:
The cheetah is the fastest of animals for a short dash and the horse has superlative
endurance. These animals differ greatly in body size, so it is instructive to compare their ways of
running. Analysis was made from slow-motion moving-picture sequences by tracing images of
successive frames and arranging them in correct spatial relation to one another. The cheetah can
sprint at 70 to 75 mph; the horse can attain 44 mph for 300 yds. The cheetah seldom runs more
than 1/4mi., the horse can run at 20.5 mph for 20mi., and its rate of travel declines only slowly as
distances increase over 30 mi. The endurance of the Mongolian wild ass is apparently superior to
that of the horse. The horse uses the transverse gallop, usually covers 19 to 25 ft. per stride and
complete about 21/4 strides per sec. At 35 mph. Its body is suspended once in each stride, during
one-quarter of the stride interval. The leading front and trailing hind limbs support the body longer
than their opposites. A change of lead usually occurs first for the front feet, but must be
anticipated well before the trailing front foot strikes the ground. The forward motion of the front
limbs as they pivot on the supporting feet raises the forequarters, but the resulting deceleration of
the body is negligible. Its mass and inertia require that the horse minimize the motion of one part
of the body relative to another and move its centre of mass in a nearly withers and croups, and
the back is relatively rigid. The cheetah uses rotary gallop, covers as much ground per stride as
the horse, and at 45 mph completes about 21/2 strides per sec. The body has two long periods of
suspension (and probably a short one) in each stride, adding up to half of the stride. The trailing
front foot is on the ground a little longer than the leading foot; the two hind feet have about equal
periods of support. Changes of lead are smoothly accomplished, and can be initiated an instant
before the trailing front foot strikes the ground. The front limbs do not raise the forequarters. Body
size is about optimum for maximum speed: it is small enough so body form and motion can be
adapted for speed with very little regard for efficiency, yet large enough to gain a long and rapid
stride, as noted below. The feet are lifted high. There is pronounced up-and-down motion of
shoulders and pelvis, and marked flexion and extension of the spine. Flexion and extension of the
back contribute to speed by: (1) increasing the swing of the limbs, thus increasing the distance
covered during suspended phases of the stride and increasing the duration of the supported
phases; (2) advancing the limbs more rapidly, since two independent groups of muscles (spine
muscles and intrinsic limb muscles) acting simultaneously can move the limbs faster than one
group acting alone; (3) contributing to increased maximum forward extension of the limbs, which
permits their greater backward acceleration before they strike the ground; (4) moving the body
forward in measuring-worm fashion; and (5) reducing the relative forward velocity of the girdles
when their respective limbs are propelling the body. Speed is the product of stride rate times
length. Relative to shoulder height, the length of the cheetah's stride is about twice that of the
horse. Factors contributing to its longer stride are: (1) two principal suspension periods per stride
instead of one; (2) greater proportion of suspension in total stride; (3) greater swing of limbs, so
they strike and leave the ground at more acute angles; and (4) flexion and extension of the spine
synchronized with action of the limbs so as to produce progressions by a measuring-worm motion
of the body. The rate of the cheetah's stride is faster than that of the horse because: (1) its
smaller muscles have faster inherent rates of contraction; (2) its limbs are moved simultaneously
by independent groups of muscles; (3) its feet move farther after starting their down strokes
before striking the ground, thus developing greater backward acceleration; (4) the forelimbs have
a negligible support role and probably actively draw the body forward; (5) the limbs are flexed
more during their recovery strokes; and (6) the shoulders and pelvis move forward slower than
other part of the body at the times that their respective limbs are propelling the body.

Hildebrand M. 1959. Motions of the running cheetah and horse. J Mamm 40(4):481-95.