Tired of traditional running? Well, maybe it's time to try using your hands instead.

That's what Shaun McCarthy and other Australian residents are doing — running on all fours. It's part of the Internet's latest fitness craze: "Crunning."

This strange new trend might just be your thighs' worst nightmare, combining a fast-paced crawl and a run that's sure to cause quite a stare ... especially when you do it in public.

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McCarthy, who hails from Melbourne, Australia, said he's the one behind the term "crunning." “It’s not crawling, it’s not running … it’s crunning,” he told TODAY.com.

Crunning is simply running using all four limbs on the ground, or “crawl-running.” McCarthy said he started the movement five weeks ago and it's been steadily growing since.

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He even created a Facebook page where he posts videos of himself practicing the trend, and shows the proper way to complete the exercise.

And as far as he knows, the crunning movement is only in Australia; however, in China, people are doing a similar move, which he describes as "crawl-walking" because of its slower pace.

McCarthy believes that crunning is a better workout than running because it puts more of an emphasis on the upper body than traditional upright running does.

“It really works your thighs and shoulders at the same time,” McCarthy said. He said that he gets a lot more exhausted after crunning, too, so he believes it must burn more calories than running.

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Crunning seems more difficult than traditional running — but is it actually a better workout? Is it safe?

Karim Baylor, a certified personal trainer at Equinox also told TODAY that “any exercise that involves full body motions leaves the chance to develop a lot of strength.”

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He warns, however, that he can’t say whether crunning is potentially harmful.

Baylor says that to avoid injury, “You definitely have to prepare your body with appropriate exercises and training with any new workout.”

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Since your hands are on the ground while crunning, McCarthy suggests wearing gloves to protect them. He hopes for people in Melbourne to continue to join the crunning movement and believes it could be a "game changer" for personal fitness.

The real question is — will a crunning movement start in the U.S.?

It’s certainly a possibility. That is, if people aren’t embarrassed to be on all fours in public.