July 10, 2009

Study To Shed Light On Cheetah’s Top Speeds

A team of British researchers is working to discover why cheetahs are the world's fastest animals.

Using high-speed cameras and a sensitive track, the scientists are studying North African cheetahs from ZSL Whipsnade Zoo, which are known to reach speeds of 64mph within just a few paces.

"The cheetah is fascinating because it can run 50% faster than any of the other animals we are familiar with, so in terms of understanding what limits how fast you can run, the cheetah is a wonderful animal to study," said Professor Alan Wilson, who heads the structure and motion lab at Britain's Royal Veterinary College (RCV), during an interview with BBC News.

The RCV team is enticing the cheetahs to run by attaching pieces of chicken wings and feet to a loop of fast-moving string pulled along an enclosure by an electric motor.   

And as the cheetahs chase their food, four high-speed cameras recording images at 1,000 frames per second, captured the wild cats' every move.  By comparison, standard cameras typically record images at just 25 frames per second.

"We use two cameras on each side of the enclosure so we can see the cheetah from both sides," Penny Hudson, a PhD student at RVC, told BBC News.

"When a cheetah gallops, it does different things with either side of its body - it has an asymmetric gait."

The RCV team also embedded custom plates within the cheetahs' running track that operate as "sophisticated weighing scales that are able to measure all the forces going through their legs," Hudson said.

The scientists plan to compare their results with other research on greyhounds, which can reach top speeds of roughly 40mph.

"Greyhounds are artificially bred by us to be fast, whereas these [cats] have evolved for that," said Hudson.

"But cheetahs can run much faster than a racing greyhound"¦so we're trying to get them running at similar speeds to see what they do that's the same and what they do that makes them go that little bit faster."

Usain Bolt, who ran 100 meters in 9.69 seconds, or about 23 mph, is the fastest human on record.  Among humans, leg strength is believed to be the limiting factor in speed.  In greyhounds, speed is constrained by how quickly the dogs can swing their legs.

However, among cheetahs the factors limiting speed are not clearly understood.

The RCV research will be used to examine the forces and dynamics of the cheetahs' legs, their speed, stride length, posture and joint angles.

"We really don't know what it is about cheetahs that make them run so fast - it might be their flexible spines, or it might be their shoulder blades, it could be that they stretch their legs a bit more, but hopefully the data will unravel some of those mysteries," Hudson said.

Although scientists have long known that cheetahs can achieve great speeds, the upper limits of their capabilities are not yet certain.

A report published in 1997 in the Journal of Zoology said the top speed for cheetahs was 64mph. The figure was based on data from a 1965 study in Kenya, where a captive cheetah was timed as it chased after a 4x4 vehicle with food attached to the back.

However, some researchers believe the cheetahs are capable of achieving even faster speeds.

Professor Wilson said that the captive cheetahs at Whipsnade were reaching 34mph.

"We know that cheetahs won't reach their full speed here. We hope they'll get to as fast as our racing greyhounds do, and we hope to get to a bigger space to do this," said Wilson, whose research is funded by the Biotechnology and Biological Sciences Research Council.

The RCV team also hopes to expand their research to include cheetahs in the wild.  Such a study would allow scientists to examine how cheetahs run and perhaps record a more accurate maximum speed.

"Eventually we'd love to be able to get GPS and video data from cheetahs in the wild that are out and hunting - this is where they will be at the limits of their performance," said Professor Wilson.


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