Got Exercise? Workouts Better for Bone Health
Teen Girls' Physical Activity Can Help Prevent Osteoporosis Later On
June 11, 2004 -- Exercise works better than
calcium in building strong bones, a new study shows. It's a new advisory for
teen girls: Physical activity is more important than drinking milk for
That finding disputes the current message
given to women and girls, writes lead researcher Tom Lloyd, PhD, an
epidemiologist with the Penn State University College of Medicine. His paper
appears in the current issue of the Journal of Pediatrics.
"Although calcium intake is often cited
as the most important factor for healthy bones, our study suggests that
exercise is really the predominant lifestyle determinant of bone strength in
young women," Lloyd says in a news release.
The advent of high-tech bone density
screening -- dual energy X-ray absorptiometry (DEXA) -- has given researchers a
tool to measure bone density and indirectly measure bone strength. That has
also helped researchers understand the importance that various factors like
calcium and physical activity play in building bone and preventing
Studies have shown that as much bone is
built between ages 13 and 15 as that which is lost to aging and osteoporosis
during the last four decades of life. Therefore, it's crucial that a girl works
on optimizing the bone-building process during adolescence as the best
protection against osteoporosis, writes Lloyd.
To better understand the factors at work,
Lloyd studied 80 girls about 12 years old when the study began.
For 10 years, he and his colleagues tracked
the girls' bone strength through yearly DEXA scans of hip bones. They also got
information on calcium intake, birth control use (which is reported to help
build bone), and physical activity the girls got -- whether it was sports,
marching band, dance, aerobics classes, running, walking, or another
Calcium intake and birth control pill use had no
significant affect on bone strength, Lloyd reports.
Sports and exercise did make a big difference --
increasing the young women's bone mineral density at the hip 3%-5
"We have shown that ages 12 to 16 are
important years for bone [building] and that adolescent physical activity is
positively related to [bone muscle density] and bone strength of the young
adult hip," writes Lloyd.
His study has one limitation: It only
involved white girls. Other ethnic and racial groups must be studied to provide
a more complete picture of osteoporosis, calcium, and physical activity, he