The researchers say their fresh perspective could lead to designing more efficient electric motors, better prostheses and new treatments for neuromuscular diseases.

Science has long theorized muscles behave largely like motors. But now Northern Arizona University researcher Kiisa Nishikawa suggests muscles act more like a spring.

"Existing theories don't explain how muscles shorten rapidly," Nishikawa said. "Muscles can only shorten to do work; they can't do work by lengthening." A spring also can only do work by shortening.

By example, Nishikawa noted the jaw muscles in toads and chameleons shorten in the lower jaw, and the opening of the jaws causes the tongue to stretch by its own momentum.

"When a toad or chameleon captures prey with its tongue, it exerts force over a distance. Figuring out how they do it has immense application to any device that actually moves."

The research that included Tom Sugar and colleagues at Arizona State University is to be highlighted by Discovery Channel Canada as part of its Daily Planet program this fall.