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Why greyhounds are speedier than humans

Greyhounds are such superb runners because of their sleek style and ability to tackle tight bends without slowing down,  British researchers said.
/ Source: Reuters

Greyhounds are such superb runners because of their sleek style and ability to tackle tight bends without slowing down, British researchers said on Wednesday.

Unlike humans who have to reduce speed at a banked curve to cope with the increased gravitational and centripetal forces on their legs, greyhounds attack a bend without changing their stride.

“Greyhounds can cope with high forces as they go around the bend whereas humans cannot and they have to slow down a lot,” said Dr. James Usherwood, a zoologist and animal motion specialist at the Royal Veterinary College in England.

“It is quite a surprise that greyhounds are not limited by the same things that humans are,” he added in an interview.

Usherwood and Dr. Alan Wilson analyzed the gait of 40 greyhounds while running a straight path and taking tight bends. Their research is reported in the science journal Nature.

Humans appear to be limited by the additional force when running around a bend and need to increase the amount of time their foot is in contact with the ground, which means they have to slow down.

Sprinters on the inside lane at a track meet are at a distinct disadvantage because as they go around a bend it is tighter than on the outside lane so they have to compensate more.

Because of this the International Association of Athletics Federations has abandoned indoor sprints that have tight bends.

Powered by torque
But greyhounds keep a constant stride on the straight and bends and withstand a 65 percent increase in limb forces.

“This supports the idea that greyhounds power locomotion by torque about the hips, so -- just as in cycling humans -- the muscles that provide the power are mechanically divorced from the structures that support weight,” Usherwood explained in the journal.

Horses, hares and greyhounds have about the same top speed at roughly 17 meters a second or about 37 miles per hour, nearly double the pace of humans, according to Usherwood.

“The fundamental differences that we have shown between what limits running speed in four legged animals and in human are important in understanding the mechanical limitations to performance and how different animals work,” Wilson said in a statement.

The researchers studied greyhounds because the dogs are so fast and easy to measure. They don’t know if their findings are specific to the breed or apply to all four-legged animals.