Senior Citizens Learning to Fall Like a Skydiver Can
Reduce Hip Fractures by 70 Percent
Parachutist's landing best reduces hip impact whether
you jumped from an airplane or tripped on a curb
July
7, 2008 - Senior citizens could reduce their risk of hip fracture by
nearly 70 percent if they learn to fall like skydivers, new research
from the University of Michigan 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 you jumped
from an airplane or tripped on a curb.
The parachutist's strategy involves crouching,
leaning so that the outside of your lower leg hits first and then
rolling onto your 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," said 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 said.
A hip fracture often occurs when a person trips and
lands on his or her side, Ashton-Miller said. 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.
Falling on a non-slippery surface, you have
seven-tenths of a second from stumble to impact, Ashton-Miller said.
Typical reaction time is two-tenths of a second. That leaves five-tenths
of a second to put the fall strategy into practice. So it's best to know
how to fall in advance.
"When you start to fall, you need to know what to
do. You can't hang around trying to decide what to do. What people tend
to think is that there's no time to do anything, and that's absolutely
not true," said Ashton-Miller, who says he learned this firsthand as an
avid skier.
The researchers tested four fall strategies. The
"broomstick" strategy involved keeping the body stiff. This was the
control. The "hip lateral flexion" strategy allowed the hips to swivel
by 30 degrees but the other joints remained stiff. The "spine and hip"
strategy confined the knees to a maximum bend of 20 degrees, but other
joints could operate normally. And the "free" strategy allowed all
joints to move freely.
When a computer simulation of a man falling was
given these constraints, it identified the free strategy as the least
likely to break a hip. And it pinpointed the parachutist's style as the
best way to allow the joints to move so the muscles dissipate energy and
thereby lower the impact force. Ashton-Miller said future experiments
and simulations will study women falling as well, and he expects the
results to be similar.
Strategies were tested with and without the use of
an arm to help break the fall. And time delays of one-, two- and
three-tenths of a second were simulated, along with the effects of age
on muscle strength.
This research was funded by the U.S. Department of
Health and Human Services.
The paper is called "Effect of pre-impact movement
strategies on the impact forces resulting from a lateral fall."
Ashton-Miller is also a research professor in the
Institute of Gerontology and in Internal Medicine at the U-M Health
System.
Michigan Engineering
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http://www.engin.umich.edu/.
Keep up with the latest news for senior citizens, baby
boomers
July
7, 2008 - Senior citizens could reduce their risk of hip fracture by
nearly 70 percent if they learn to fall like skydivers, new research
from the University of Michigan suggests. 
