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 team of University of Arkansas researchers recently
released a study that will have everyone digging for bones. Digging,
planting, weeding and watering, that is.
 The
researchers have linked regular yard work to the prevention of
osteoporosis, finding that women aged 50 and older who gardened
at least once a week showed higher bone density readings than
those who performed other types of exercise - including jogging,
swimming, walking and aerobics.
Research has
long shown that weight-bearing exercise can help women maintain
healthy bones. But the University of Arkansas study represents
the first to determine which types of weight-bearing exercise
have the strongest impact on bone density, said Lori Turner,
assistant professor of health sciences and lead researcher on
the project.
By knowing
which exercises provide the greatest benefit, women can design
a workout regimen that will ensure strong bones as they age.
Such preventative measures may reduce the number of people who
develop osteoporosis - a debilitating disease that currently
threatens more than 28 million Americans.
"Within
our study, more than half the women - 57 percent showed low bone
density. There's no question that osteoporosis is a problem in
our society," Turner said. "But if we persist only
in treating this disease, the number of victims will never drop.
We have to find ways to prevent it."
To gain a
comprehensive look at the effects of exercise on older women,
Turner needed a large field of subjects. She found it in the
National Health and Nutrition Examination Survey - a dataset
collected by the National Center for Health Statistics, which
contains information on more than 40,000 women.
Turner first
weeded out the youngest subjects, leaving a pool 3,310 women
aged 50 and older. She then examined how often these women performed
different activities, including yard work, calisthenics, bicycling,
dancing, aerobics, swimming, jogging, walking and weight training.
Turner compared
each activity to bone mass, finding that bicycling, aerobics,
dancing, yard work and weight training were linked to higher
levels of mineral density. The researchers then performed a regression
model analysis - a statistical assessment that examined each
activity independently, ensuring that no two overlapped.
The results
showed only two activities to be significant for maintaining
healthy bone mass - yard work and weight training. "We hadn't
expected yard work to be significant," Turner said. "It's
taken for such a dainty activity. But there's a lot of weight-bearing
motion going on in the garden digging holes, pulling weeds, pushing
a mower."
An additional
benefit of gardening is the fact that it's performed outdoors,
said Turner. Exposure to sunlight boosts vitamin D production,
which aids the body in calcium absorption.
While weight-bearing
activity and vitamin D work directly to strengthen women's bones,
yard work provides indirect benefits as well. Of all the activities,
yard work proved the most popular, with nearly half of the subjects
- 1,384 women claiming to garden at least once a week. Such popularity
makes it a highly effective preventative measure.
In recommending
exercise options to older women, health professionals must consider
three factors: the activity's effect on bone density, its safety
and the likelihood that people will stick with it.
For instance,
other studies have shown that jogging helps maintain bone density.
But its high-impact nature carries greater risk of injury, particularly
for older women. In addition, 50-year-old women who have never
jogged are unlikely to adhere to a jogging routine for any length
of time.
But Turner
considers yard work an ideal activity that matches all three
health concerns. "The best thing about yard work is that
so many people are willing to do it. They don't dread it as exercise,"
she said. "People have other motivations for gardening.
They take pride in a beautiful yard and pleasure in being outdoors.
They'll probably continue to do it as long as they're able."
To read more
about Lori Turner's research, please visit http://pigtrail.uark.edu/news/1999/OCT99/bones.html
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