Scientists Look For Answers As Kangaroos Hop To It
Newcastle Herald
Thursday October 7, 1999
AS people spend hundreds of dollars at city gyms, highly trained kangaroos are being tested on running machines at the University of NSW in efforts to understand why and how they hop.
Professor of Zoology Terry Dawson and his students have tested a mob of kangaroos on treadmills, ranging from two-metre-tall reds through to the woylie, or brush-tailed bettong.
Their results are crucial to an understanding of how mammals, including us, propel through the environment and how muscles respond to strenuous exercise.
Professor Dawson and his team have found the kangaroo defies all accepted laws of locomotion.
The motion of kangaroos is almost as efficient as that of animals that fly.
The only mammal more athletic than a kangaroo is a horse.
Humans are not so hot in terms of energy cost at speed, being midway between rats and dogs.
Science defines hopping as two legs moving together in synchrony and the kangaroo family is the only group of large mammals that is known to have hopped.
Because of the spring when a kangaroo makes a bound it recovers up to 50% of the energy it uses for one stride and uses it again for the next.
A big roo can travel through the desert, making five-metre bounds, for kilometres on end at 45kmh, way faster than what the world's best human sprinters can muster for 100 metres.
It can take up to a month of daily practice, slowly building up the speed of the treadmill before the captive-bred kangaroos are used to the concept of enforced motion in a laboratory.
Once they get their rhythm on the fitness circuit they are monitored for oxygen consumption, stride length and frequency.
Postgraduate student Koa Webster has trained six of the bettongs and gives each 15 minutes on the treadmill almost daily.
A red kangaroo on the treadmill can hop as many as 120 times a minute.
The scientists have various treadmills for the different species and can bring them up to speeds approaching the marsupial maximum in the wild.
When all other mammals hit their straps and increase their speed they immediately begin to use extra energy.
`Kangaroos go faster without any increase in cost,' Professor Dawson said. `They also decrease the time that their feet are in contact with the ground. They're the only animal that doesn't fit the theory of the costs of running.
`Until kangaroos fit into the theory then we haven't got a theory.'
© 1999 Newcastle Herald