[PHNUTR-L] Exercise in childhood and adolescence may stave off osteoporosis

[Kathrynne Holden, MS, RD]

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Public release date: 5-Jun-2006
http://www.eurekalert.org/pub_releases/2006-06/iof-eic060506.php

Contact: Andrew Leopold
aleopold at webershandwick.com
416-964-6444
International Osteoporosis Foundation

Exercise in childhood and adolescence may stave off osteoporosis

Recent studies indicate that exercise can help build and maintain 
healthy bones. But just how early should one start? At the IOF World 
Congress on Osteoporosis in Toronto, Canada this week, several studies 
highlighted the importance of exercise in children and adolescents for 
building peak bone mass that will help protect against osteoporosis in 
later life.

Researchers at Wright State University School of Medicine in Ohio, 
U.S.A., have found that leisure activity has a significant impact on the 
rate of bone mass increase in both girls and boys. Lead author Miryoung 
Lee and colleague followed a group of 99 children, aged 8 to 18, to 
determine how changes in physical activity affects their bone mineral 
density, a measure of bone strength. For both sexes, the rate of bone 
accumulation was found to be higher with increasing leisure activity 
level (see conference Abstract No. P191).

In girls, more intense physical activity that is associated with sports 
also leads to greater increases in bone density. Similar effects were 
not seen in boys taking part in sports. "During childhood and 
adolescence, children's bodies grow rapidly and bone mass is accumulated 
quickly. The amount of bone built during adolescence and early adulthood 
is one of the most important factors related to the risk of developing 
osteoporosis in later years. These findings confirm that physical 
activity is important for optimal bone accrual during childhood, 
consequently leading to higher peak bone mass," said Lee.

The researchers also found that for an average follow-up period of four 
years, physical activity levels were not significantly different between 
boys and girls. "It is, however, more important for girls to exercise 
during childhood because they are at greater risk of osteoporosis later 
in life," Lee said.

Finnish study corroborates exercise benefits in building strong bones

Researchers from Finland also emphasized how important it is to not only 
start but maintain regular exercise. Marjo Lehtonen-Veromaa and 
colleagues at Turku University Central Hospital, found that over a 
period of four years, girls who stopped exercising had a much lower 
increase in bone content than those who maintained their physical 
activity (see conference Abstract No. P673).

At six month intervals for three years, and then once again after seven 
years, Lehtonen-Veromaa recorded physical activity among 142 girls. The 
researchers also measured the bone mineral content of the thigh bone and 
lumbar spine at the start of the study and at the three, and seven year 
time points. They found that the third of the girls who exercised most 
had the highest increase in thigh bone mineral content over the seven 
years (24 percent increase). In the third of girls who exercised the 
least, that increase was only about 16 percent.

During the course of the study, physical activity among 30 of the girls 
fell by more than 50 percent and by 25-50 percent in another 29 girls. 
The researchers found that the effect of this reduction in activity was 
pronounced. In the 30 girls who were exercising the least by the end of 
the study, bone mineral content of both the thigh and the lumbar spine 
were significantly lower than in the girls who maintained their level of 
physical activity. This effect was more pronounced at the thigh bone.

"It is understandable that girls who exercised intensively during the 
prepubertal period are disposed to change their exercise habits a few 
years later, since the objects of their interest will change easily 
during puberty," said Lehtonen-Veromaa. She suggests that if young girls 
get tired of one kind of physical exercise, they should search, either 
by themselves or with their parents, for another type of physical 
activity that may be interesting enough to pursue. "It is of great 
importance to continue a physically active way of living because it 
seems to be deleterious for bone health if the magnitude of physical 
activity descends deeply, added Lehtonen-Veromaa.

Brazilian study shows benefits of exercise

And in keeping with current theories that bone built up during ones 
youth puts one in good stead when older, Fernando Siqueira and 
colleagues from the Federal University of Pelotas, Brazil, reported that 
exercise in childhood and adolescence can reduce the risk for late life 
osteoporosis (see conference Abstract No. P260). Siqueira and colleagues 
questioned over 1,000 individuals aged 50 and over in southern Brazil 
and matched their osteoporosis history with their history of physical 
activity between ages 10 and 19, as judged from an internationally 
recognized physical activity questionnaire.

Sigueira and colleagues found that those volunteers who were active in 
adolescence had a 45 percent lower risk for osteoporosis.

Recognizing the importance of exercise for bone health, World 
Osteoporosis Day 2005 was dedicated to the theme Move it or lose it. The 
IOF published "Move it or Lose it," a guide to how exercise benefits 
bones of all ages. Part of our "Invest in Your Bones" series, the guide 
explains how exercise helps to build and maintain strong bones, helps 
prevent falls and fractures, and speeds rehabilitation. Copies can be 
found on the IOF website.
-- 
Kathrynne Holden, MS, RD < fivestar at nutritionucanlivewith.com >
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