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Updated 11:00 AM June 30, 2008




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Falling like a skydiver reduces risk of hip fracture
See a demonstration of the parachutist's landing style >

Senior citizens could reduce their risk of hip fracture by nearly 70 percent if they learn to fall like skydivers, research suggests.

In the first study to examine the effectiveness of different sideways fall strategies, computer simulations showed that the parachutist’s landing method best reduces hip impact whether jumping from an airplane or tripping on a curb.

The parachutist’s strategy involves crouching, leaning so the outside lower leg hits first then rolling onto the person’s backside. In the simulations, landing in this position subjected the hip to just 25 percent of the force necessary to break it.

“A hip fracture can mark the beginning of a downward spiral. If you fall and break a hip and you’re over 65, you have a 20 percent chance of not surviving another year and another 20 percent chance of not regaining your mobility,” says James Ashton-Miller, a professor in the departments of biomedical engineering and mechanical engineering. Ashton-Miller is an author of a paper on the research published in the Journal of Biomechanics.

“In this study, we asked whether it matters what you do in the air after you start to fall. We found that a parachutist’s landing style reduces your risk of injury, and you can land a fall safely with or without your hands,” he says.

A hip fracture often occurs when a person trips and lands on his or her side, says Ashton-Miller, who also is a research professor in the Institute of Gerontology and in internal medicine at the U-M Health System. The study showed that the typical reduction in muscle strength that occurs with age does not impair an individual’s ability to accomplish the safest strategy.

The study also found that reaction time is as important as the body’s position during a fall. A delay of more than two-tenths of a second in deploying the parachutist’s strategy increased the impact force of the fall by at least 70 percent.

People who fall on a non-slippery surface have seven-tenths of a second from stumble to impact, Ashton-Miller says. Typical reaction time is two-tenths of a second. That leaves five-tenths of a second to put the fall strategy into practice.

“When you start to fall, you need to know what to do,” says Ashton-Miller, who says he learned this firsthand as an avid skier.

The paper is called “Effect of pre-impact movement strategies on the impact forces resulting from a lateral fall.”

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