[video]http://www.youtube.com/watch?v=0v_pOLOCXnQ[/video]
Despite their similar size and morphology, cheetahs can effortlessly outrun greyhounds.
A new study gives clues to the mechanical differences that enable these swift felines to achieve their maximum recorded speed of 29 meters per second (65 miles per hour).
Scientists in the United Kingdom and South Africa compared the sprint style of captive cheetahs with trained greyhounds to better understand the potential limits to running speeds in four-legged animals.
“Cheetahs and greyhounds are known to use a rotary gallop and physically they are remarkably similar, yet there is this bewitching difference in maximum speed of almost a factor of two,” said study co-author Alan Wilson from the Royal Veterinary College, London, in a press release.
The researchers enticed the big cats to chase a lure across force plates while filming at 1,000 frames per second. Measurements of their body motion and footfall patterns were taken, as well as the forces on their limbs.
“Force plates are cosseted, loved pieces of equipment that people don’t generally take outside of the lab and bury in the ground in the English summer,” Wilson joked.
This process was repeated with greyhounds, but filming at 350 frames per second.
Surprisingly, the dogs’ maximum speed was faster than the cats’ at 19 meters per second (42.5 miles per hour) compared with 17.8 meters per second (40 miles per hour).
Looking at stride patterns, the team found the cheetahs’ strides were slightly longer with a slightly lower frequency.
However, as they accelerate, the big cats increase frequency from 2.4 strides per second at 9 meters per second (20 miles per hour) up to 3.2 strides per second at their top speed. In contrast, the dogs stayed at around 3.5 strides per second throughout their range.
In the wild, Wilson believes cheetahs may reach 4 strides per second, which could explain their greater top speeds. The captive cats probably failed to run anywhere near record speeds because they lack motivation.
“They have lived in a zoo for several generations and have never had to run to catch food,” Wilson said. “The next stage is to try to make measurements in wild cheetahs in the hope of seeing higher speeds.”
The study was published in the Journal of Experimental Biology on June 21 and can be accessed here.
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