Young gymnasts show high bone density

NEW YORK (Reuters Health) - The high-impact tumbling of gymnastics may boost young girls' muscle mass and bone density, according to a small study.

Spanish researchers found that young girls who participated in artistic gymnastics had greater muscle mass and bone density than their peers whose activities were limited to gym class.

What's more, they also had denser bones and more muscle than girls who practiced rhythmic gymnastics, a sport that requires fitness and agility but does not include the particularly high-impact moves of artistic gymnastics.

The findings suggest that before they reach puberty, girls should take up activities that put some stress on the bones in order to strengthen them, the study authors report in the International Journal of Sports Medicine.

Like muscle, bones respond to exercise by becoming stronger, particularly higher-impact activities like jumping and sprinting. The years before puberty are an especially opportune time to boost bone density with exercise, explained the study's lead author, Dr. German Vicente-Rodriguez of the University of Zaragoza.

For girls, building bone density from an early age may reduce their risk of the bone-thinning disease osteoporosis later in life.

Any sports that include jumping, sprinting and rapid direction changes may aid in bone development, Vicente-Rodriguez told Reuters Health. That includes soccer, basketball, martial arts and lacrosse, among others.

Swimming and bicycling, because they do not require the body to work against gravity, are not good bone-builders, Vicente-Rodriguez noted. Nonetheless, since they do improve cardiovascular fitness, they're still healthy activities.

The current findings are based on fitness tests and bone and muscle scans from 35 prepubescent girls -- nine who were part of artistic gymnastic clubs, 13 who practiced rhythmic gymnastics and 13 who did not exercise outside of school.

Overall, the researchers found, both groups of gymnasts were more physically fit than their sedentary peers, and had substantially less body fat. However, the artistic gymnasts had the greatest muscle mass and tended to have higher bone density, particularly in the arms.

This doesn't mean, however, that the tumbling of artistic gymnastics is necessarily "healthier" for girls, according to Vicente-Rodriguez. Instead, he said, children should take up a variety of activities, with both low and high impact. "The most important thing is that sports participation should be always encouraged."

SOURCE: International Journal of Sports Medicine, May 2007.