December 7, 2005

Greyhounds tackle high speed bends better than humans

By Patricia Reaney

LONDON (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

"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 analysed the gait of 40
greyhounds while running a straight path and taking tight
bends. Their research is reported in the science journal

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

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

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

Horses, hares and greyhounds have about the same top speed
at roughly 17 meters a second or about 60 kilometers per hour
(37 mph), nearly double the pace of humans, according to

"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

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.