Twisted act.

Looks like "Elastic Girl" from The Incredibles has some competition! Last spring, a young girl twisted her body into a pretzel shape while practicing for the Mongolian National Circus in Ulan Bator.

What is her supple secret? This contortionist has an amazing range of motion. That means her bones, muscles, and other body tissues can work together to bend her body into far-reaching poses.

Like you, her skeletal system comprises 206 bones, which meet up at joints. Different joints allow various amounts of motion.

For instance, your shoulder joints can move 180 degrees out from the body, but elbows can flex only 130 degrees, says Daniel Green, an orthopedic surgeon in New York.

Ropelike connective tissue called ligaments fastens your bones together at each joint. These connectors contain collagen, a fibrous protein, which adds flexibility to joints. As you move, the stretchy straps lengthen to give your joints mobility. They also keep joints from moving past a "safe" range.

So how can rubberlike performers bend farther than the accepted range? "About 5 to 10 percent of the population have looser ligaments than others," says Green. With such elastic ligaments connecting her vertebrae, this girl can arch her spine's bones into a tight U-shape.

Although moves like that would be dangerous for the average person to attempt, these well-trained performers don't usually get injured while contorting. Perhaps, Green says, it's because during practice they stretch slowly into each pose. However, they aren't safe from all harm: People with hyper-flexibility are more likely to get hurt while playing sports. For instance, the force of a football tackle could easily rotate their joints out of alignment, leading to a torn ligament.

If you're thinking about folding into a butterfly shape, think again. No amount of stretching will give the average person extra-elastic ligaments. But to increase your flexibility, Elizabeth Ignacio, an orthopedic surgeon in California, advises slow and consistent daily stretching.

Although you will be more nimble, you'll still have to leave the Elastic-Girl-like feats to the pliable experts.