BOULDER – If you've ever wondered whether kangaroos' tails actually serve a purpose (and really, who hasn't?!), then you finally have a definitive answer.

A new study involving scientists from the University of Colorado, Simon Fraser University in Canada and Australia's University of New South Wales have found that – even though they seem awkward – kangaroos actually use their tails as a sort of fifth leg to help propel them across the landscape.

"We went into this thinking the tail was primarily used like a strut, a balancing pole or a one-legged milking stool," said Associate Professor Rodger Kram of CU-Boulder's Department of Integrative Physiology, a study co-author, in a news release. "What we didn't expect to find was how much power the tails of the kangaroos were producing. It was pretty darn surprising."

The study began in 1973, when Professor Terence Dawson of the University of South Wales studied how kangaroos walk on a treadmill.

Some 40 years later, the team trained five red kangaroos to walk forward on a force-measuring platform with Plexiglas slides. This measured the force that came from the legs and tails of the animals.

"I'm envious of kangaroos," said Kram, a competitive master runner in the mile and 1,500 meters. "When they hop faster, they don't use energy at a faster rate. The have the ability to move faster and not get tired, the ultimate goal of a runner."

Watch the kangaroos walk here: